Each time someone gains a level of contamination, they roll 1d6. If the result is equal to or less than the character's total contamination levels, they gain a mutation.

Treat these Contamination Levels as half (rounded down). Thus you would need to gain 12 Contamination Levels to undergo a Monstrous Transformation, instead of 6.

Only specific magic can remove contamination levels.

Creatures do not recover naturally. The purge contamination spell can remove contamination, but it leaves affected characters exhausted.