Chompzone

For me, it has to be the Worldbreaker gun. Just look at this beast, it's so beautiful. Back in the EA era, it took me years until I finally somehow got this card and then I insisted on using it everywhere possible. I was aware that it's not the best course of action, buy hey, it's worth for the style points alone. 

Hi Radical, thank you for bringing these important points up. 
I've been contemplating writing a post on changing frost t1, so I won’t hijack your thread with that. The essence of my idea was also to buff the Ice Guardian (IG) in exchange for keeping the rather ill thought through home soil nerf. My idea in a nut shell:
1      1 Always let IG spawn with its shield enabled (instead of only near friendly bases)
2      2 Disallow the spawning of IGs within a 40 meter (2x coldsnap radius) radius of enemy power wells. This limitation would be overruled when the frost player has a well inside that radius, so IGs can still always be spawned in defense.
Point 1 would allow frost to contend for a small amount of the (initial) field (battle) and end the complete dependence frost has on taking the first well they can get to, as in the current state of the game frost can’t (reasonably) hold their own on the field. Which leads to the subsequent abusive situations of always leaving frost open to rushes, whether it is a swift spam that runs in between your bases until a well drops or a direct rush that becomes possible thanks to 100 power frost just invested in a well. Not to mention the more often than not situation of getting locked out of the map, which is especially noticable on maps like Haladur where the frost player has to take the first well that is conveniently located right at the base of a choke point that leads to the rest of the map. A choke point which on the other end conveniently has 2 wells & an orb for frost's enemy to take and lock them out.
Point 2 is optional (imo) and might be too restrictive for frost and/or too difficult to implement. But I want to prevent any potential abusive situations of dropping IGs on to enemy wells, even though this concern might be exaggerated as Frost has no swift units to quickly approach wells with.
Could you perhaps elaborate your idea on IG? As I am quite sure IG received multiple nerfs, and I’d like to read your exact idea.
Mortar & Phase
With regards to Mortar and Phase tower, I can only agree. I think it is fair to say that both towers are too efficient so I would suggest the following:
Phase tower – increase the power cost to 75, this would at least decrease the vast efficiency difference between the phase tower and its opposing armies. This would also decrease the spam-a-bility of the card.
Mortar tower – increase the power cost to 80, this would achieve the same efficiency equalizer and spam demotivator. The reason I think mortar tower should cost more than phase is because you often only need 1 mortar to heavily influence a game, considering its vast range, large AoE and large amount of spike damage.
The reason I think we should go for power cost increases as a first iteration of balance is because it is simple to implement, and just as simple to roll back or fine tune. This would dramatically increase the speed at which (these) balance iterations can be rolled out and evaluated, and most importantly will save the dedicated devs time, subsequently increasing the likelihood of the changes actually being implemented. 
PS: A small example of what Radical described in mortar camp shutting down t1 battles vs Frost (and t2 for that matter)