I like the game features but I think there is some serious balancing issues.
It is a lot of rng to get the tower you need or the same tower in order to get them to level 2 and fuse them- and fused towers can have some really crack abilities that you absolutely need for late game. I must have rerolled 10 times and not get any stack tower.
Virus is just overpowered. I got to first place, first time playing, simply because I got virus, and half of the new runs I failed was because I encountered my original team. I finally surpassed my old record because I managed to get virus again in my deck.
Trying to do hypercarry (frontline tank + support) is really, really difficult. It is just so easy to do damage in this game. PWR isn't even the primary source of damage for most builds. Half of the towers have some crazy instant kill type thing where they get 10 PWR (guardian angel and doomguard) or treant's 5 thorns, and who can forget petrify
My suggestions would be: Let player choose any for the first tower, cause otherwise it will just lead to rerolling, and curb the classes whose whole gimmick is doing as much damage as possible to one specific unit.