Very cool game, but a few points:
First a bug report on ratbone, his bone can be launched outside of the dungeon walls if you throw the bone when jumping into the ceiling, leaving you unarmed. I think letting the player teleport the bone back by holding the attack button would work well to mitigate that, and it's annoying to have to hunt down the bone anyways if it travels a ways away while hunting down enemies.
Second, Rollerpig is not too interesting since you can hold the roll indefinitely. I think giving him a stamina bar that lasts for perhaps 4-5 seconds would be a fair compromise, having a recharge/cooldown once emptied of 1.5 seconds.
Swarmbug is interesting, but it has a very hard time dealing with swarms of enemies ironically, and that can be a BIG problem if you start a level with a bunch of enemies falling down a hole (Which has happened with some runs), leaving you without space to escape and breathe. I think letting the player launch bugs more forcefully as you press attack by pressing a side direction would work well, have such bugs push back enemies a tiny bit at least so you can handle a wave of foes more practically.
Nothing on the chicken, he's pretty perfect, maybe not letting the player slash as fast as they can tap the button would balance the chicken more, but it's still vulnerable enough having to deal with multiple angles at times.