How does "Resist % Element" work?

[Onionsoilder]

I always assumed that it simply took that % off the total damage, so for example, if you have a spell that does 30% damage, and a unit that is 20% resistant to that damage type, the spell did 24% damage. But in practice, it seems to be more... My unit with Resist Magic seems to be taking 8-12% damage instead of 22-26% damage. Does it act cumulatively then, so instead of reducing it by 20%, it takes a full 20% off? Or what?

 

[Earthling]

Think other promos mod magic resistance a little, and also damage is not constant, but random. So a spell that does an average of 15%/max 30% (thinking of Maelstrom here I think) doesn't ALWAYS do that much - sometimes it would do 4% anyway, sometimes 19%, and then I guess resistances applied on that.

In short I don't much know the exact formula and I act on the assumption it'll be random; always hit with multiple casts of the spell if possible to ensure full damage done.

Also I never take Resist Magic promos ever because they are worthless/the AI won't use magic enough anyway, and they are too hard to get. Stack-damaging magic of course is uber-powerful when you use it though.

 

[PPQ_Purple]

One thing I would suggest is moding your FFH by changing a spell to do constant damage.
I think it could be done via python.

Than observe the results and experiment with it.