[SixOfSpades]

Sarevok's chance of scoring a Deathbringer Assault is actually 3% on each melee hit. And it's 200 Piercing damage, so critters like Mustard Jellies are still gonna laugh at you.

As for the choice of whether or not to use him: If you've never done X before, then by all means you should try X and see what happens.

As for whom to swap out, I would actually give Mazzy the boot, from a powergaming perspective. You're certianly not lacking in Tanking power, so one must look to secondary skills--and most of this game is melee-oriented, so being good with Gesen isn't as useful as Valygar's Stealth and excellent Elemental resists, or Keldorn's anti-Mage abilities and Carsomyr.