Decay was always one of those weird effects, seemingly straightforward but also difficult to balance properly. Limit healing too much and it becomes a death sentence, but how do you do it without defeating the spirit of the effect? I've finally figured out a simple way to strike a good balance:
Decay
The affected character becomes unable to benefit from Recover, Renew Limb, or Renew Body, and only regains a single health whenever an effect would restore health, regardless of the amount that would normally be restored (e.g., Drain, Heal, Revive Full, Share).
Thus, lifesaving measures are still effective, but a Decaying character won't be able to substantially recover from wounds until the effect is lifted. No matter how you're healed, you only regain one health per application.
As a Warlock, I completely support this revision. I like it much better than the original action.