[Taqwus]

I've probably mentioned this before. But...

Casters should avoid casting spells which make a friendly unit that's currently immune to an attack form, suddenly vulnerable to that attack forum (notably: barkskin, protection, mass protection; all reduce fire resistance). You shouldn't keep a nature mage around your Abysian army as things stand right now.

Note 1. If resistances stacked multiplicatively, and were applied to damage directly so 100% damage resistance => x0 multiplier for damage, 100% vulnerability = x2 multiplier etc., then this wouldn't be an issue.

Note 2. If they still stack the current way, even checking the current resistance might not be enough; it might cause problems if the player had scripted a ward spell to grant immunity (perhaps by stacking with an existing sub-100% resistance).