Hello,

Apotheosis bosses are a really fun mechanic, providing a nice challenge for good loot, however they're very vulnerable to suffocation damage; a player can easily trap any boss in a 1x1x2 box and suffocate said bosses with gravel, sand, or any modded block affected by gravity.
I think that giving them a resistance to this type of dmg or denying drops when killed this way may prove to improve the mod. (Which, by the way, I'm really fond of!)