You were walking around and suddenly found yourself in a frozen void, there was nothing but snow until you met... Her...

Do note:

Void Metal - In it's raw form, the most volatile of metals, that can corrode and take over the mind, as well as grow inside of people when exposed to the raw metal, has a chance to mutate it's victims. Completely safe once properly processed.

Stage 1 - Small Parts of the Body grow Void Metal, barely painful, but uncomfortable.

Stage 2 - The void metal gets larger and grows more painfully, covering nearly the entire body.

Stage 3 - Mutations begin, the body is morphed and twisted into a distorted creature, but retains some human features.

Stage 4 - Complete Mutation, they are now but a monster made of Void Metal, mutated and disfigured.