As two actions, you can create a vial of black and white liquid that continuously swirls. A creature can drink the contents as an action to be granted a measure of protection from death.
The first time the creature would drop to 0 health as a result of taking damage, the creature instead drops to 1 health, and the effect ends.
If the effect 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 effect ends.
You can expend 1 additional catalyst so the target gains 3d10 temporary health when it drops to 1 health.