Mutation

Mutation is kind of a mechanic for Cult of the Possessed hero and impressive units. When any of them reach Rank 1, 4 or 7, it's granted one of few possible mutations, which alter its stats, appearance and sometimes its ability to use certain equipment.

With introduction of the 4th Patch (v1.1.4.13) mutations are now received on ranks 1, 4 and 7 respectively. Effect is retroactive on saved games.

Arm Mutations
These change one of your arms into unique kind of weapon, which cannot be removed. It also limits you to be able to equip only an Armband in the weapon slot of a mutated limb.

Ripper mutation is available only to Possessed and Chaos Spawn.

Extra Arm
This mutation, available to Possessed and Chaos Spawn only, gives your right hand one more forearm, which works as upgrade for your main weapon.

Torso
Torso mutations limit character armour, allowing only the use of Cloth armour.

Head
Head mutations disallow the use of a Helmet.