"Defeat Vahlok" is an objective in the side quest "Lost Legacy" in Elder Scrolls V: Skyrim - Dragonborn.
Walkthrough
This room is filled with traps which makes getting around very difficult without taking additional damage.
Move carefully around the area, the safest place is going to be moving along the edge of the pool. Be warned that Vahlok can summon in a Flame Atronach. Remember about the traps that are all around the area. Keep off the central portion of any part of the walkway. You will want a lot of health potions to make it through this fight.
