Hey nice suggestion there! I enjoyed playing that TD a lot, it was brilliant! Especially the Ronalds in the bonus round :-D There are quite a few people who'd enjoy tower upgrades in Mazebert TD. Evolving would be taking this idea one step further I guess. I have this on my list, but it's not top priority (it will take a huge deal of effort to create/balance those upgrades).
I hear you! I'm just pleased to be part of the community here. This is one of those special gems on Android. And I think very fondly of those Ronald's! Lol
A simplier form of evovling a tower could maybe come from other cards. Meaning say you have a Hitman..build 2 more hitman ontop of it and it becomes a Hired Gun..or for simplicity of cards and not forgetting which is the base could just name it Hitman 2. Add another 5 hitmen to it and now its an Assassin, or Hitman 3, then add 10 to it etc.. The base stats of the next tier would go up as well as its buffs, like for hitman its 25 crit, hitman 2 could be 30 or 35..and hitman 3 or later stages could even add more things like multicrit 1-5 based on how evolved you make it. So now the player has 2 options. Take the old cards and transmute them for higher rarity cards, or use them and evolve your current towers.
That's a great idea! Like build a Hitman on top of another hitman and he becomes a hitman+1... Maybe just palette swapped... Do it again and he becomes a hitman +2.. And at some point (4 seems reasonable) He becomes an assassin! That gives me an idea for the card ability... If assassin hits a creep with a critical hit he gets va 3% damage buff that stacks but resets if he goes 10 second without a critical... Stole that from Borderlands, but whatever!