- “Unkillable Only” does heal HP, but only after you die – and it stops working at positive HP (Unkillable 2) or full HP (Unkillable 3).
- A target reduced -10xHP by corrosion damage is gone: dissolved, disintegrated, or vaporized. Resurrection is impossible.
- Each point of success grants a minute of Unkillable 1 and Regeneration (Very Fast), both with Cosmic, Works on the dead (+50%).
- If he heals to above -HP, he returns to life.
- To keep this ability balanced, “Cosmic, Works on the dead” means it only works on the dead – not injured living people – and gives one try, ever. If the subject fails his HT roll or regains too few HP to revive, he’s dead for good.
Canonically, you should use the prices in Limited Defenses (p. B46). However, as Unkillable influences the outcome of accumulated wounds, and thus could be worked around easily ("Crushing damage can't kill him, so just kick him a lot and then poke him with this pin."), it really ought to be more severe. I'd kick in an extra -20% and have the -80% level become a perk – Unkillable (Dragon's Fire)  sounds really cheap until you realize that you can still be taken out of the fight by dragon's fire and merely get a free pass on dying from it until the dragon gets around to stepping on your unconscious body.
- Aggravated Injury (better get Cosmic Defensive!)