When attempting this achievement, there are an insufficient number of Risen Zombies within the first area of Stratholme where the 10 waves are fought. However, more can be found in the mini gauntlet after Chrono-Lord Epoch.
With the massive changes to this instance with the 4.0 Patch, it would seem near impossible to accomplish this achievement with a purely random group. Although some modifications could be made depending on group composition, it's very much still achievable.
The first nine waves should be treated as normal, with disregard to killing as many zombies as needed to make it through the instance. Upon the spawning of Salramm the Flesh-Crafter, all DPS should run to the cast-iron gate west of the entrance to the inn where Arthas first fights the Infinite Dragonflight. The tank and healer should run to Salramm and pull him to the DPS, at the gate. Hold Salramm at the gate for two minutes, attempting to do as little damage to Salramm as possible, and to single target down every add. Leave zombies alive. After two minutes have passed, burn down Salramm, and hug the left wall into the inn. Proceed through the instance, until Chrono-Lord Epoch is defeated. At this point, split the group into two groups: 1) A healer and a DPS; 2) Everyone else. The healer should run through the first half of the dungeon, and pick up all 85 zombies, while the second group moves with Arthas to the clearing, but the second group should NOT start the gauntlet. The first group should finish up gathering zombies, and begin AoE'ing, at the same time the second group pushes into the gauntlet, killing as many zombies as possible - at least 15.
- How to: Zombiefest Heroic Culling of Stratholme
- (Remake) How to: Zombiefest Heroic Culling of Stratholme
- Patch 3.0.2 (2008-10-14): Added.