You can’t avoid Vyemm’s AoE, but you can pretty much ignore it. Once the tank has engaged, run to the back of Vyemm’s lair. You will get knocked back like everyone else but you can just keep shooting. Eventually the knockbacks will put you into the corner pictured below with several people in it. You can run to this location if you’d like to expedite the process.
Listen for a tank needing to get back to Vyemm, they can be knocked into this corner as well and several people can make it difficult for them to return to the boss. Especially if it’s a stubby dwarf like Korros. In this case, move to let the tank back in.
Zeal map location:
Your view of the fight from the corner:
