Trolls and Vampires in the Enemy Expansion mod use separate mobs as a way to change their states. For example, the Troll has a regular and enraged state as separate mobs, which it switches between and copies the health over from the mob it's overriding. However, there seems to be some interaction going on between Enemy Expansion and IDF that causes the new enemy state to be spawned with full health instead of the health it previously had. This does not happen unless IDF is installed and running.

config options from 0.2.6 should be able to fix it, otherwise reopen this issue 👍

Ah, that would make sense. IDF edits the attributes of mobs when they enter the world. During this process, they get healed to full HP because their max HP usually becomes higher than what it was before the editing. I will work on a fix.