1. 6 heart containers is really not enough to play the game normally, like you can't even place two hollowed poops, and that's my favourite unit
2. Null is kinda pointless, babies still atack him while he's invisible
3. Fiend baby and double baby both need a buff, fiend just sucks for his cost, and the double is too hard to unlock for it being this ineffective
4. Revenant needs a nerf, i think he should kill not only enemies but, just like in original Isaac, also kill your units who are standing is the way of his attack
5. Stone enemies need to be a little easier or a little less of them on a level, they resist everything, have very powerful abilities and a ton of hp, i would also say that frosty should either ignore your units who are not babies, or jump back not that far when he attacks, if you have dirty mind he literally jumps off screen and takes forever to come back