1. Firstly, he certainly does, I'd just need to go hunt down the scan. The "lol this is a random power you can't resist it" doesn't work on a verse that unironically provides saves to Broadway Force, Vibration Manipulation, Duplication, and bad smells. Secondly, the
use of the power can be resisted. He can't do anything to Vecna because of that alone. Say he believes Vecna doesn't have any powers. Vecna resists power null. So either way this is a moot point.
2. Cool. Nothing stops Vecna from incapping the avatar though. Or just going outside the multiverse. Inter-multiversal travel is a thing, hell, look at demons. Look at
Elminster. The former travelled through the 1-A far realm from a broken multiverse to create the Abyss, the latter was capable of travelling to another D&D setting and even, as you put it, real life (canonically) to give interviews to Dragon Magazine. Don't ask.
3. Vecna's passives aren't assault passives, and Vecna resists. If Akabane has a wincondition, which it seems he might depending on what he believes, since we've given it such a wide breadth, then this wouldn't be a stomp and instead a victory for Vecna.
