Aside from completely agreeing with Navaar that we really need a ranked system first to have some data and that the dynamics in 2vs2 are quite different, I would also like to add that imo we should do small, incremental nerfs&buffs, like +5 or -5 energy, instead of the huge +30 energy nerfs called for here. It is much easier to keep a card playable that way, and if necessary you can just repeat the nerf until it seems fine. Just nuking a card from orbit really reduces variety, especially considering that the cards talked about here are one of a relatively low number of turrets that are actually viable at all in PvP. Killing phase tower and mortar leaves ... makeshift and what else? Cannon Tower with Nature Frost and CoN with Shadow Frost?
I would honestly prefer some building counter in nature and/or frost t1, like a timeshifter spirit that only keeps buildings from attacking in a certain range. Or a frost spell that makes units much more resilient against building attacks and disables knockback from them. Not so strong that it becomes an auto include and makes beating buildings easy for them, but strong enough to use it meta dependent and counter tower spamming.