Deterioration

Rank	Effect	Flavor
1	Periodic temporary stat loss.	Your body is slowly deteriorating.
2	More frequent temporary stat loss.	Your body is deteriorating.
3	Most frequent temporary stat loss.	Your body is rapidly deteriorating.
A ring of sustain abilities will negate this. Natural recovery from stat loss tends to keep rank 1 in check. Ranks 2 and 3 will eventually kill you via stat death if allowed to progress unchecked.
Bad mutation