Tank is a symptom combo exclusive to the Necroa Virus DLC which allows some zombies to greatly increase strength and body mass. Severity increases when this combo is in play. Anabolic Boost and Bone Dysplasia are required. The achievement Tank is earned for forming the combo.
- This combo is named after the eponymous zombie from Valve's Left 4 Dead franchise. Said zombie has has massive strength, high durability and extreme agility for his size.