Play as Inferno.

Nah... We won't have time to cast Armageddon to reduce defense (it won't affect ours anyway), and it's not worth leveling up other Chaos spells with that much magic. It's more realistic to fight on a large arena where there will be an opportunity to counter. It would also be good to have a ring against morale and a cloak of deadly shadows, and the Staff of the Underworld. Otherwise, the elf with his morale will just overwhelm us.
I still think Chaos won't help: killing 6 levels for it isn't worth it. I rarely play against elves in the very late game because I don't particularly like long games. I only have one acquaintance who likes elves in HotS, but he doesn't like to play for a long time, so the game ends up being a matter of luck... I don't know, it's been a while since I played that matchup, I need to try to kill some time, but Chaos, in my opinion, won't help.