D&Dtools1

The energy of life flows through you, warming your hand—and indeed your very soul.
But instead of swiftly infusing that life into others to heal their wounds, you feed it slowly and gradually into your ally.
You implant a tiny seed of positive energy into the subject's soul.
This seed of life grants the subject fast healing 2 for the duration of the spell, in much the same way as vigor.
At any point before the duration expires, the subject can exhaust the remaining positive energy in a sudden burst of healing as a standard action.
When this option is exercised, roll a number of d4s equal to one-half the spell's remaining duration, rounded down (for example, 5d4 if the spell has 11 rounds remaining).
The result is the number of hit points of damage instantly healed.
Using this option ends the spell immediately.