Does mitigate trigger on damage dealt to a hero that is immune to it? Like say you mitigate and the T-Rex chomps on a danger sensed Legacy is the reduction still spent? (I'd say yes but I wanted to be sure)
No, Legacy would not be dealt any damage thanks to being immune. So the Mitigate would still reduce damage for someone else.
I would say no, as Legacy is not actually being dealt damage. On the other hand, if Legacy would be dealt 1 damage, and fortitude reduces it by 1, mitigate would still trigger. Because being immune prevents the damage alltogether, and preventing functions differently than taking it. It's like with Fright Train and Hippocratic oath; preventing the damage that would be dealt to Fright Train does not cause the first-time-each-turn damage buff to be used up, but reducing it to 0 (like with the environment or something) would.
That's my interpretation, anyway. Not official by any means.
Damn, I got Ronway'd.
GODDAMMIT ROSSWAY
Game Grumps reference.
But yes, I agree with them. Damage prevention or immunity doesn't spend it but reduction does (even if some other reduction reduces it to zero).