Warhammer: Vermintide 2

Hooray for Luck based achievements!

(Note: achievement must be done on Legend difficulty)

When fighting BubbleButt HailSquirt, he opens the fight with a Plague Storm attack, followed up by teleporting around the room and casting his Plague Wave attacks (technically, he teleports after casting his Plague Wave attack, but we need not be pedantic here). Do enough damage, and he'll teleport to the rafters and summon mobs.

Whatever you do, try not to kill these mobs. A good Ironbreaker is useful here as his Taunt will take the mobs off the squishies and allow him to kite them around the room solo. Even better, have an Ironbreaker with a Concentration pot to keep them off the squishies for extended periods of time.

During the time he's in the rafters, BubbleBath HaggisSack will cast Pestilence Possession (Its the slow, round projectile). Did you know you can melee attack these to get rid of them? Safer though to use ranged to clear them out. If they hit you, you'll be paralyzed -- but just get your teammate to light attack you to free yourself. During this tie, try to keep an eye on the Ironbreaker kiter so he doesn't get stuck and overwhelmed in case one of the pestilence projectiles hits him.

Now the luck part -- after a time, Barbeque HalfScrotum will teleport down from the rafters to the middle of the arena. From here, he can cast two different spells, either Plague Storm again (what you don't want) or Scourge Squall (what you do want). You'll know its Scourge Squall is you see a green circle fill the center of the room (Plague Storm fires projectiles at you again).

If it's Scourge Squall, just have the Ironbreaker run into the circle, and he and the mobs will be easily sucked up in the tornado. If you didn't kill the mobs yet, there should be more than plenty to get you to the 15 needed for the achievement.

If you're not running with an Ironbreaker, or if taunt isn't running, the safest way to ensure the tornado picks up all the mobs is for everyone to run into it. The tornado damage is minimum for Legend, so unless things are going really bad, you should survive this without issue.

Sadly, it took us about three to four attempts of this fight to get Benedict HumbleScratch to cast his tornado. Hopefully, you'll have better luck the we had.

The achievement unlocks during the fight right after the tornado, but remember you still need to finish the level to get credit for it for the Empire Resurgent achievement, so go ahead and finish off BabbleBitch HodorSlap, grab your dice, and get to the Bridge of Shadows.