What is dead may never die

You touch a creature and grant it a measure of protection from death.

The first time the target would drop to 0 hit points as a result of taking damage, the target instead becomes incapacitated but stable. At the start of their next turn  the target of the spell arises with 10hit point, and the only action they can take is Disengage or dodge. 

If the spell is still in effect when the target is subjected to an effect that would kill it instantaneously without dealing damage, that effect is instead negated against the target, and the spell ends.