Tranquil Sprites

Convoke
Prevent all damage to target friendly creature. All damage the creature would've taken this turn is instead gained as health. If this card's cost was
paid by convoke, shuffle this card into your
library.
I've come across these beings a few times. I'm lead to believe they are spirits, but I cannot decipher their
motive. I do know that they bring feelings of peace, tranquility, and drowsiness to those that come across
them, even in the moment of distress.