| Instantly heals any and all wounds suffered by the caster, but also permanently lessens their resilience to injury, to a degree dependent on (and inversely related to) power.
It is powerful enough to literally pull someone out of Death's Door, although the shock will briefly confuse and paralyse the caster. It has no effect on the undead.
Higher spell power may reduce the max HP loss this spell inflicts. With every casting, the game makes nine checks with an 8/Spell Power chance of failure. Your lost max HP equals the number of failed checks +2, meaning you are guaranteed to lose somewhere between 2 and 11 percent of your max HP. Your current HP will then be set to your new max.
This spell will have no effect if you are already at max HP or if you have less than 20 max HP. The undead and characters in lich form cannot cast this spell, as they are beyond the realm of normal life and death. Casting it while under the effect of Death's Door works, but you will be paralyzed(5-9 turns) and confused(10-19 turns). A source of clarity will prevent the confusion, but only Formicids can avoid the paralysis.
Prior to 0.14 it was a level 7 spell.