Originally Posted by
Conzar
There was a bug with Zombiefest, when they wouldn't come through the Inn, but it has since been fixed. There are 85 zombies on the starting side of the inn, and so you need 15 (plus any you don't manage to pick up on the way). I don't think it is impossible, but would be pretty hard as a non-tank, due to the elite-mobs on the other side (you get 3 or 4 of them before you'll have enough zombies to qualify for the achievement).
Less-rabi: Doesn't he try to change at 75%, 50%, 25%? So keeping your dps DOWN makes this easier (as your interrupt cooldowns have a chance to clear).