You searched for TRICK DEATH
1. trick death
When a mobile is affected by trick death, it has temporary immunity to
death, meaning that if its hitpoints go down to 0, it will be restored to
full health and the immunity effect will wear off. This spell does not work
on players. To see if your familiar is affected by anything, you can use
'affect <familiar name>'. This spell cannot be cast on normal monsters, it
can only be cast on familiars.