Vitality

When an ally takes damage, you can use this cantrip as a reaction to lessen the blow.  As a reaction to the attack hitting, but before damage is rolled, you can spend 1 point from your Healing Pool and grant the ally 1D4 temporary HP that last until the start of your next turn.  At the start of your next turn, if any of the temporary HP is left, the temporary HP vanishes and the character heals 1 HP.  If your healing pool is empty, the spell can still be cast but when the temporary HP vanishes the character does not heal.

Healing Pool Ritual:  Once per Long Rest, the character performs a ritual in which they may spend their own Hit Dice + Constitution Modifier to put into a Healing Pool.  This Healing pool works just like a Paladins Lay on Hands ability.  If a character has access to Lay on Hands from a class feature or otherwise this ability increases the Lay on Hands healing pool and Vitality spell uses HP from the Lay on Hands ability instead.