Celestial Death is a concept included in Celestial Injury and Death.
It works entirely different from standard death rules (failing a HT roll and dying)
Soul hits going to 0 or less causes the following results
- a Will roll must be made: failure causes stun for 1 turn
- an aging roll (from B83) based on Will instead of HT must be made
- it says "his attributes may be reduced" so this may mean a failure results in ALL attributes going down, instead of the normal policy of making separate HT rolls for each attribute
- an aging roll is made separately for each realm of Power Investiture they have
- this includes Corporeal Investiture and Ethereal Power Investiture and Power Investiture (Celestial)
- Soul hits reset to Will + Extra Hit Points
Losing all CI prevents going to (or remaining on) material plane, requiring a Superior to grant a level to restore the ability.
Losing all EPI gives Absent-Mindedness and Partial Amnesia until at least 1 level is regained
- lingering memory damage even after EPI recovers is GM/player option
Losing all PIC shatters Heart and makes them a Remnant
- if they have a vessel they can survive using P16 rules
- if they don't they die final death
Any of ST/IQ/DX/HT dropping to zero causes soul-death (forces composing the soul unravel) and only God can possibly revoke it.
There is mention that beings lacking a trait cannot "go negative" in it, even though the ramifications appear to happen at ZERO levels rather than negative levels.
The Human soul is immune to this (losing Celestial Investiture does not make them into a Remnant, just removes the ability) which should be accounted for when designing these abilities for 4E conversions.