NHF – new heroes for Heroes V 3.1.

Based on my observations, Plague provides 25/50/75% protection against magic, but deals full damage to creatures.
I'm sending a file with an array of standard creature names (index - creature ID).

This is a fact. Plague damage is not reduced by any effects, and in particular, it ignores any similar resistances. However, the Plague itself (when cast) can be deflected, and it also doesn't affect creatures that are immune to it (undead, constructs, elementals).