Battle Aid

You touch an ally creature and channel their inner life force to cause a surge of natural healing. It can spend one of its Hit Dice, rolling the die and adding their Constitution modifier to the result.The creature can't regain hit points from this spell again until it finishes a short or long rest.

A creature touched by this spell can spend one additional Hit Die when you reach 5th level (2), 11th level (3), and 17th level (4).