Namor /Bishop/Blade w/ GR according to this thread (i dont have them, cant confirm)
Ebony Maw/Domino/IMIW only on non-contact attacks should theoretically work (havent tried)
Luke Cage (and CM movie to a lesser extent) timed correctly w/ invincible
CM doesnt but she does get additional energy
Void/Quake technically never has to touch anyone
Red Skull (awakened)/Hyperion/Mordo and the 2 Stranges if you could get to special 3s without hitting him
Havok and Invisible Woman i believe can mitigate some of it
Elektra? I think she reduces ability accuracy somehow but not sure
Ghost (awakened) if you can somehow never get hit + build up to special 3 from phasing
Technically anyone with a regen+DoT debuff should be able to survive long enough without having to actually hit him, but arent guaranteed to reduce the damage back
As far as anyone fully immune to energy or damage back from Electro, as in all their attacks dont trigger it....none
EDIT: Oh my bad, you said "hero". I dont have time to re-edit bc comments get locked within 15 mins and theres like 1 min left
Comments
AA granted you land enough neurotoxins
CB with enough furies
BW has a 75% max
GP increases chances up to 100% based on combo
Namor /Bishop/Blade w/ GR according to this thread (i dont have them, cant confirm)
Ebony Maw/Domino/IMIW only on non-contact attacks should theoretically work (havent tried)
Luke Cage (and CM movie to a lesser extent) timed correctly w/ invincible
CM doesnt but she does get additional energy
Void/Quake technically never has to touch anyone
Red Skull (awakened)/Hyperion/Mordo and the 2 Stranges if you could get to special 3s without hitting him
Havok and Invisible Woman i believe can mitigate some of it
Elektra? I think she reduces ability accuracy somehow but not sure
Ghost (awakened) if you can somehow never get hit + build up to special 3 from phasing
Technically anyone with a regen+DoT debuff should be able to survive long enough without having to actually hit him, but arent guaranteed to reduce the damage back
As far as anyone fully immune to energy or damage back from Electro, as in all their attacks dont trigger it....none
EDIT: Oh my bad, you said "hero". I dont have time to re-edit bc comments get locked within 15 mins and theres like 1 min left
Continuously spam sp1 by power gain