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You can have 1 squad of Silverwind Lancers and have them hold position near the orb. The knockdown will split them apart, but since they're holding position they won't get back together, so they no longer get hit by the aoe extra damage. You can then ignore all of that since the squad will easily survive until Moon shows up without the need for any heals. You can then use the lancers at the end to get the final orb if you're going for a dragonkin clear without ground presence and you haven't got it already.
Also, for the beginning, my favorite way of doing it is by grabbing the 2 power wells right at the start with a barrier, then defending them with a tower and your Lyrish dudes. No need to spawn any units if your positioning is good, since you can kill all the creeps before they can fatally damage your well. Also, you only need to use one stone of torment if you place it next to the large units and keep your archers on the wall. The small guys get teleported to it and everything dies in time. No upgrades needed.

I have a really easy strategy for Mo. It is kinda slow (30 min for the map), but you really can't fail it at all.
The very easy variant requires amii monument (or enlightment if you have even more patience), which is quite expensive.
Also, for the sake of speed, you should think of a method to heal Mo quickly at t3 and below. Shamans + power well were enough for me; wheel of gifts and equilibrium (b) were used at t3 (regrowth can also be used early when going for amii monument). I think it is also very possible without any expensive cards with more patience.
Again, the replay is in the attachments.
All defense is done using Mark of the Keeper. I use juice tanks for extra power at the end, but it isn't necessary. Windweavers for early Mo support. Giant Wyrm for clearing the map and boss. Shrine of Memory for keeping void empty (cultist master + furnace of flesh is also great for this), but isn't necessary as you can just wait. Breeding grounds is nice for extra power. Curse of Oink can really help with getting t3. Wheel of gifts for all it's goodness (mostly healing Mo). Incredible Mo can be used for even more defense. Amii monument to trivialize the end. If not going for this, living towers + root nexus (b) can really help your defense at the last wall a lot. Lastly, some good healing spells, like regrowth and equilibrium (b).
I start the mission by letting Mo destroy the white tower. Meanwhile I spawn some windweavers and shamans to aid Mo. After clearing this, I move my units far to the right so they don't get killed by the next tower. I also place a MotK above my monument. Destroy the next tower and let Mo kill the Soulhunter. I let my archers help killing the spearman. At this power well, flying units continually spawn. I place a MotK left/above the powerwell and buy it. Then I make Mo attack the northern tower and when I arrive there, I stampede towards the other tower/healing building. Then I quickly send Mo back to the earlier power well to bait the enemies away from the cannon. After killing the enemies, I destroy the cannon. Then kill the newly spawned birds and purchase the powerwell and monument. I go for ice here, so I can place juice tanks at every well. I place a MotK to the left of the power well. Then I let Mo heal up, pass the monument and build a MotK to the right of the monument. After destroying the enemy building blocking the miniboss, I walk up to the healing building with Mo and stampede the tower and spawner. With correct MotK placement, the AI of the windhunter that spawns on the left breaks. I focus the paralyzing units and shielding witches while I Oink the two bandit lieutenants. Then I buy the power well and place another MotK and juice tank there. Finally I buy the monument. You can also place a MotK here, but the birds that come all the way here are severely damaged and get easily killed by my remaining windweaver.
Now comes the second miniboss. First bait the Soulhunter and Windhunter away from the cannon and kill them with Mo. Heal Mo back up to full. In this time, I start building Wheels and a shrine of memory. I prioritize the healing and defense buffs. When Mo is at full health again, I go to the cannon and stampede it, kill the paralyze unit and destroy the other tower. On the way back for healing I destroy the anti air turret as well. In my case I didn't even need the healing and went straight to the turtle. Mo really doesn't take much damage from the Banzai birds, so I just tank the hits. After hiding and healing at the gold chest, I go north with the only goal of destroying all buildings. This is the only risk I took. I could've also waited for the amii monument and use t4 units, but Mo is really tanky and you can easily heal up with spells if needed. After destroying all towers I run away to fully heal and come back with a small army to kill the Banzai lord. I don't know if the well on the way gets destroyed by the Banzai birds, but I just bought it after killing the boss.
Now for the last part. If you don't destroy the wall and create a strong air force to fly over it and kill the camps behind it, nobody can attack you. After a while Mo will break the wall on its own. I don't know if you can block him using buildings and if that will result in a softlock. I just moved Mo back to safety again and didn't build the wall. Nobody seemed to attack any of the buildings I made at the power wells. I leisurely kill some camps and the bandit walker after which the boss can be fought. I still cleared everything, which should be really easy now as all units fled. I created a very strong army for the boss, because I remembered from my advanced playthrough it being very hard. However, when I showed up, the bandit walker didn't come back and I could easily kill the Ravenhart ships. This might be because I skipped breaking the last wall normally.
mo.pmv

As you wrote that you are not happy with the Soultree description, you can replace it by this. The replay is also provided in the attachments. Note that this was my first try so I make some mistakes. The text below contains some improvements over the replay.
This strategy requires resource booster and stone of torment. Shamans are helpful to heal the unit which will take hits from Viridia. I had a lot of void power (>600), so anything which can empty void is recommended (shrine of memories, cultist master+furnace of flesh etc.).
When you gain control, put all Lyrish squads on the wall. Immediately send the squad near the monuments on it's way, as it will reach the wall just in time. Spawn a unit and walk it halfway across the bridge. I choose a nightguard (g), as it is swift and can later be used to gain a strong enemy unit.
I choose to select all archers and kill enemies one at the time. This saves some HP on the wall, but you can do without. It is important to focus the archers in the second wave to prevent any squads from dying. Between the first and second or second and third wave, you can hide your unit behind the power wells on the other side of the bridge. Wait till the third wave comes and build the monument. When this is finished, build 2 stones of torment so that all large units are in the range of both. Return all Lyrish squads back to base, as they will die from the stones of torment. I choose to kill some enemies while waiting, but this isn't necessary. I kept the unit at the monument until all enemies died, so I could use it to bait some runaway enemies to the stones of torment. Meanwhile, you should have places resource boosters at the 2x2 power wells as soon as enough power was available to do so. After placing these, buy the power well across the bridge and place a resource booster, then buy the last well and monument. Once the wells next to resource boosters are empty, destroy the boosters. This will return the power to your void.
Now you'll need an army to defeat a grinder and some other units. Don't help Viridia venture north, as she will only reach the strong units earlier. I placed a breeding ground and spawned Mo. I used my nightguard to take a flamethrower enemy. With these and some healing and lightning I managed to defeat all enemies. Then I buy the power wells and monument and summon a shaman. This shaman can outheal the damage of Viridia on the flamethrower. You can also use the 2 Lyrish squads to tank some hits if all survived till this point.
Meanwhile, start building an army to take the last camp over. I used the Mo to stampede some buildings, but this is very difficult as his "spells" get blocked by the enemies. You have plenty of time to kill this last camp and buy the last monument. After this, the mission is complete.
Edit 1 (thanks to Speed112): If you use a squat unit like silverwind lancers and putting them on "hold position", Viridia will knock them back away from eachother. After a while, the horses will be outside of the hitbox of the squat. As Viridia always hits a horse and not the squat hitbox, the squat won't take any damage.
Edit 2: You can use amii monument to build T5 instead of clearing the last camp and buying the orb there.
soultree.pmv

I did Defending hope first try with the following cards.
Windweaves, shaman, retreating circle, breeding grounds, living tower, both affinity root nexus, hammerfall, deepcoil worm, curse of oink, any healing spell (just in case), juice tank (can do without if buying wells outside base) and wheel of gifts (can probably do without).
First I send a windweaver to either side. While clearing the first enemies, I buy the wells. After that I build the walls, buy 1 monument and build a breeding grounds. When this is finished, I summon 2 windweaver squats and 1 shaman for each wall. This is enough defense for quite some time. Meanwhile, I summon 3 deepcoil worm (2 might be sufficient). With these, I kill any of the 4 spawners. Oink as many enemies as possible, kill the spawner and retreating circle back. In the meanwhile, I build living towers at my walls along with root nexi. I always build 2-3 living towers on 1 wall before supporting the next, as living towers get stronger if there are more present. Root nexus can connect bottom and top towers.
After killing the 4 spawners, I free Rogan and continue defending. With 2 deepcoil, 5 living towers, 2 wind weavers and 2 shaman at either side, defenses should be good. When the northern keeps break, I replace it with hammerfall. Whenever I had extra power, I built wheels, but extra XL t3 units will probably do fine (maybe even better).
Replay attached below.
defending hope exp.pmv

Very easy and I think even cheap (in bfp) strategy for Slave Master provided through the attached replay file. Here, we even messed some small parts up a bit, such as the start and me going for 2nd slave camp before getting t4 for my mate. We did use some expensive cards, but none were vital for the strategy. Construct and ensnaring roots were the only "expensive" cards which the defense relied upon. I like to use grimvine or colossus to go through the fire trap, but Mo can be used, especially with the charge (break wall beforehand and start charge just before going into the fire).
The general route from OP still applies, however, we never go for the teal route.
One thing to note, don't kill any bandit or camps which aren't directly in the way. In the replay, you can see that even the camp next to first t4 (which doesn't attack without provoking) can fight twilight dragons if needed.
First build some units which can clear the first camp, nothing special. Turn the fire trap on. TURN THIS TRAP OFF WHEN DRAGONS START SPAWNING. If it goes on for too long (sometimes even after 3 dragon spawns), the slaves might die. After turning it off, the defender should stop helping the attacker and start building a defense.
The defender will always defend t2, but at the start this is trivial (mostly snipers and witches), so he can help the attacker push faster.
Then leave some units at t1 because it will get attacked, but wait for the first wave of enemies first (we forgot this).
After this, make fire stalkers to kill any towers and spawners on the right hill. Use some cheap units as bait for the snipers so the firestalkers survive. Don't kill anything on the right. These bandits can help kill some twilight if things go wrong and they are no trouble for us.
Then, buy the power well over the hill on the right side and clear till you get to the north-western shielded fire trap. The attacker should have t4 now and the defender t3. When you get close to t4, dinos are released, Just run away and let the dinos fight the bandits and return shortly after to kill the remaining NPCs.
I decided to start clearing the area around the shielded fire trap with a flying t4, but it might be better to clear t4 for defender first. Don't go through the wall (or break it) to the teleporter and the "boss" on the way to t4. Also, don't clear behind t4, if you go to for there is a chance of starting the end sequence.
Now clear the part of the 2nd slave camp where the slaves have to walk and kill the slave master (can't free the slaves yet, is for later). This is a relatively small part. When this is done, flying units can start clearing the northern teleporter (if they are near the slaves) and ground units can go to the wall which was previously ignored. Go to Ravenheart en free the slaves. On your way there, kill all scoutships. Note that mines spawn by the slave under the Ravenheart, so be prepared to heal him if necessary. Bring the slaves to the portal and retried with all units except one tank unit. It doesn't matter if this unit dies. I like to add Mo and all the slaves to a group, as they sometimes get distracted to start walking somewhere else entirely. In the meanwhile, be sure to send a unit to the second slave camp. Sometimes this unit can't break the cages. Maybe it happens if he arrives before the mission tells you to free them, but I'm not sure. It is always solved if I send Mo there in this case. Free the slaves and send them to the teleporter. If you do this correctly. the "boss" doesn't even leave his camp (see replay for exact details if it doesn't work out). Ignore Moon babbling about a southern path through another flame trap and just take the short path to the teleporter.
GG, map complete.
While the attacker was doing all of this, the defender just has to spam towers (Mark of the Keeper might help) and use really strong t4. Usually, these are very slow/immobile. We used constructs which decimated the camp+twilight. Entangle will help a ton with killing the twilight abominations before getting a strong enough defense. If defense starts failing it is no problem at all, as long as the twilight can be delayed unit the second group of slaves if brought to the portal.
Note, never kill any units in the end sequence, unless you are 100% sure you don't have Mo or any slave selected. If you accidentally kill Mo or any of the slaves, it will insta-fail the mission.
slave.pmv

Very easy and I think even cheap (in bfp) strategy for Slave Master provided through the attached replay file. Here, we even messed some small parts up a bit, such as the start and me going for 2nd slave camp before getting t4 for my mate. We did use some expensive cards, but none were vital for the strategy. Construct and ensnaring roots were the only "expensive" cards which the defense relied upon. I like to use grimvine or colossus to go through the fire trap, but Mo can be used, especially with the charge (break wall beforehand and start charge just before going into the fire).
The general route from OP still applies, however, we never go for the teal route.
One thing to note, don't kill any bandit or camps which aren't directly in the way. In the replay, you can see that even the camp next to first t4 (which doesn't attack without provoking) can fight twilight dragons if needed.
First build some units which can clear the first camp, nothing special. Turn the fire trap on. TURN THIS TRAP OFF WHEN DRAGONS START SPAWNING. If it goes on for too long (sometimes even after 3 dragon spawns), the slaves might die. After turning it off, the defender should stop helping the attacker and start building a defense.
The defender will always defend t2, but at the start this is trivial (mostly snipers and witches), so he can help the attacker push faster.
Then leave some units at t1 because it will get attacked, but wait for the first wave of enemies first (we forgot this).
After this, make fire stalkers to kill any towers and spawners on the right hill. Use some cheap units as bait for the snipers so the firestalkers survive. Don't kill anything on the right. These bandits can help kill some twilight if things go wrong and they are no trouble for us.
Then, buy the power well over the hill on the right side and clear till you get to the north-western shielded fire trap. The attacker should have t4 now and the defender t3. When you get close to t4, dinos are released, Just run away and let the dinos fight the bandits and return shortly after to kill the remaining NPCs.
I decided to start clearing the area around the shielded fire trap with a flying t4, but it might be better to clear t4 for defender first. Don't go through the wall (or break it) to the teleporter and the "boss" on the way to t4. Also, don't clear behind t4, if you go to for there is a chance of starting the end sequence.
Now clear the part of the 2nd slave camp where the slaves have to walk and kill the slave master (can't free the slaves yet, is for later). This is a relatively small part. When this is done, flying units can start clearing the northern teleporter (if they are near the slaves) and ground units can go to the wall which was previously ignored. Go to Ravenheart en free the slaves. On your way there, kill all scoutships. Note that mines spawn by the slave under the Ravenheart, so be prepared to heal him if necessary. Bring the slaves to the portal and retried with all units except one tank unit. It doesn't matter if this unit dies. I like to add Mo and all the slaves to a group, as they sometimes get distracted to start walking somewhere else entirely. In the meanwhile, be sure to send a unit to the second slave camp. Sometimes this unit can't break the cages. Maybe it happens if he arrives before the mission tells you to free them, but I'm not sure. It is always solved if I send Mo there in this case. Free the slaves and send them to the teleporter. If you do this correctly. the "boss" doesn't even leave his camp (see replay for exact details if it doesn't work out). Ignore Moon babbling about a southern path through another flame trap and just take the short path to the teleporter.
GG, map complete.
While the attacker was doing all of this, the defender just has to spam towers (Mark of the Keeper might help) and use really strong t4. Usually, these are very slow/immobile. We used constructs which decimated the camp+twilight. Entangle will help a ton with killing the twilight abominations before getting a strong enough defense. If defense starts failing it is no problem at all, as long as the twilight can be delayed unit the second group of slaves if brought to the portal.
Note, never kill any units in the end sequence, unless you are 100% sure you don't have Mo or any slave selected. If you accidentally kill Mo or any of the slaves, it will insta-fail the mission.
slave.pmv

So first of all thanks to Dallarian for this great guide and everyone who helped with the information. I've been playing battleforge since EA times, but did learn a lot new tricks here. 
I want to add two tricks for players struggling with the Nighmare maps. I've beaten both maps on expert solo with them.
1) Nightmare Shard:
In Nightmare Shard the witch spawn group/patrol consists of 1 Twilight Witch, 2 Vilebloods and after a while 2 Twilight Whisperers. There are 4 witch patrols (1 from each camp type?). They spawn alternating at east and west camps. If you don't kill the witches, no new patrols will spawn.
The easiest way to do this is to kill only the witches on the east side (easy to do at your wall in the blue rectangle) and to trap the witches on the west side with MotK and a bait (e.g. Primal Defender). If the bait is within the aggro-radius, the witch will walk inside the MotK and therefore can't attack, walk away and draws aggro again. 
The best spot I found for MotK is on the south-west cliff. I placed the Primal Defender in Skywatch-mode right next to it. Be carefull for air units, if they kill the bait, the witches will walk to the Shard resulting in a loss. I solved this with a total of 2 MotK and 2 Primal Defenders. 

If you've successfully trapped all 4 witches, only single crawlers and single air units will come for you. That means you can essentially just walk through the map at your own pace.
The best point is this: You can start with the Mana Wing strategy and after that there's enough time for building the MotK and Primal Defender on the cliff.
I actually never tried the strategy with a second player, but I guess it'll become even easier.
A warning at this point: Moon is very annoying if you trap witches close to the shard... You can see it kind of in the screenshot.
 
2) Nightmare's End
This map is indeed a pain but instead of defending your T1 against these strong waves, you can also just trap the first waves. There are actually just 4 spawn waves coming to your T1 - 2 from the south and 2 from the north. At the beginning a spawn waves consists of 2 melee squads and 1 Shaman. If you kill them, soon bigger waves with large enemies will come. If you trap them, no new waves will bother you. I did this with 3 Shamans in the north and 3 Shamans in the south for the first wave. As soon as the second wave reaches the first wave, I added 2 more Shamans and 1 non-attacking Dryad to each side. A bit of micro may be needed.
If you successfully trapped the waves like this, you can take the T2 in the middle of the map. No spawn will bother you at this point, so you can just build up several thousand energy and steamroll the map. I recommend taking T3 for Amii-Monument in the northwest without destroying the shrine and then step-by-step build up T4 defence at each spawn point. You can see an example of a perfectly working defense in the screenshot below. Also you can get a glimpse of my Fire Stalker army and if you look closely at the time: over 30 minutes have passed and I didn't need to upgrade my defenses over this.
 
Another warning: Do NOT underestimate the waves at the end. Even if you build T4-towers all over the map, you may still need strong units.
 
 
PS: I think of myself as a mediocre player because I'm neither good at micro nor good at multi-tasking. Meaning everyone can learn how to do even the Nightmare maps solo on expert atleast with these tricks.
PPS: I didn't optimize these strategies, probably there are even easier version of them (e.g. MotK usage may make it easier to trap the waves).
 
                                                                                                        
 

Twelve Players Maps 2/2
Passage to Darkness
Ascension
 
Ascension Expert 1.pmv Ascension Expert 2.pmv Ascension Expert 3.pmv
Passage to Darkness Expert.pmv

Four Players Maps 3.95/8
Bad Harvest - work in progress
King of the Giants
Titans
Blight
Empire
The Dwarven Riddle - Reference only

Expect little to no progress until February.
Blight Fr3.pmv Blight FN1.pmv Titans Expert.pmv Blight Fr1.pmv Empire Expert.pmv Titans Expert Frost 4.pmv
Blight S2.pmv King of the Giants Expert.pmv King of the Giants Expert Perfect.pmv Blight S4.pmv
Bad Harvest Expert Frost.pmv

Addendum Encounters with Twilight - I played this on expert with just the starter cards with deck level 0 (first map I played after reset - first to do it on expert):
The spawn on the southeast is the key to complete the 2nd part of the map because the Whisperers and Vileblood respawn there. I pulled in the Vileblood and Twilight whsiperers to let Rogan handle them while i sneaked past with 4 Firestalkers and ran the bottom path to the spawn camp with the Abomination. CC the L and XL units at the spawn camp while attacking the camp on max range with fire stalkers. I think I used 1-2 Surge of Light to keep them alive long enough. Afterwards you can clear everything with windweavers or whatever unit you prefer. Vileblood and Whisperers are taken care of and you can clear the big camp with the Abomination after clearing t3. Swampdrakes sleep in combination with Curse of Oink and a couple Magma Hurlers are enough if you lure them out and take out the 2 L-units you pull first before focusing your attention on the Abomination.
Addendum Behind Enemy Lines:
The map becomes much easier if you refrain from killing the spawn buildings at your t2 and t3 as killing those triggers stronger waves. You can see this in a replay from @RadicalX: https://www.youtube.com/watch?v=oHd7xVPuIdc
Addendum Crusade:
Defense in the South - You can trap incomes if you do not kill the archers completely and only kill the melee units. You can achieve this easiest with Mark of the Keeper and taking the wall. The Archers will start running around but never attack anything (make sure to kill them once all the camps are down, otherwise the endwave doesnt trigger) You can also do this with Nomads as demonstrated here: https://www.youtube.com/watch?v=g52hVdIKqq4
Frost you can use Warden's Sigil, Shadow you can decimate the archers as shown in video above and just place 2 Embalmer's Shrine or somthing similar. It takes a while to take them down.
 
Addendum Sunbridge:
Even if you use the Gate trick on the right side at around 6 minutes an archer will come through and if it gets to your monument on the very right side on the map (if you already build it), it will pull the camp on top of it. You can prevent this by placing a unit at the gate to take care of that archer.
Also you can use t1 towers to outrange archers at the wall. Phase tower with their relocation is especially good. Termite hill works wonders on those as well. If you start nature t1 you can use hurricane to blow archers of the walls and make the clear way easier. Furthermore the wall breaks down after you destroyed exactly half of the segments. You can use this to stay out of range of 1 half of the archers on the wall, if you positions yourself properly.

The longer the gate is open within its 30 second cycle before the 2nd shrine is defeated the stronger the income will be that attacks you. The side that is attacked depends on which side the gate was last open when the last shrine was destroyed.
Addendum  - Convoy:
After the Grinder teleports in the middle path you can shoot him with Rifle Cultists' ability from the outside to end the map a bit earlier.
You can also use undead army at the beginning of the map and then scythe fiends ability to get in that area and then prevent walkers from advancing with placing buildings at the bottom at the bottom at the path. Left player can then shoot with Rifle Cultists from the outside to destroy the shrine after capturing t4. The walker block essentially eliminates any time limit you have on the map and makes this map pretty much unloseable.
 
Overall a good initial overview for maps that should help newer players to get a idea on what is going on on these maps and to avoid replaying map starts over and over again or be stuck in them for 40 minutes+.
I think especially the Nightmare maps are very bothersome if you do not understand whats going on and what to do (tbf they are bothersome even if you know).
Looking forward for what you have for some of the 4 player maps.
 

Two players maps 7/7
Crusade
Sunbridge
Nightmare Shard
Nightmare's End
Slave Master
Convoy
The Insane God
 
Sunbridge Expert.pmv The Insane God Expert.pmv Convoy Expert.pmv Crusade Expert.pmv Nightmare Shard Expert.pmv Nightmare's End Expert.pmv Slave Master Expert.pmv Nightmare Shard Expert Mana Wing.pmv Nightmares End Expert 25.pmv

The strategy for Raven's End is very easy (because it is one of the easiest expert maps) and might be nice to put up as it rewards a legendary card.
Conquering the middle lane first should be no problem and any deck can do it (maybe give some tips like having knockback resistant units for the enemy fire stalkers). Then move the shield so it blocks the center camp (on the bottom) from reaching T1. Prepare for an attack from an Ravenheart. It can be killed this first attack by using oink/freeze and a strong enough force, but if it flees at 50% health it is also fine, as killing it later is easier (it will regenerate to full health). Then go to T2 for the second player and take your time to build a solid defense from the center part. After is this set up, one of the player (or both if defense is strong enough/multitasking skills are good enough) can easily conquer the remaining bases.
Lending out a monument to your teammate greatly reduces the map's difficulty, as T4 can be acquired before conquering the top camp this way. Also, T3 turrets (or even T4 if you dare to risk your last monument) can be build to defend from the center.
It is very important not to do the center until all other monuments are bought, as clearing this area will start the end sequence. It is possible to clear most of it early to prevent some spawns; just leave the two towers near the portal on the bottom alive. Clearing the center is not recommended though, as all spawn camps have to be destroyed to prevent attacks and this will be very difficult with low tiers. However, given the right deck it is possible to do and saves having to defend. When doing this strategy, it is possible to keep the bosses alive, as they will not leave their camp to attack your base (just rush the spawners).
 

Thanks for the resources.
I'll just try to learn one of them and write a guide myself.