Spirit Warrior's Embrace

Delve
On each upkeep, create a 1/1 colorless Spirit
creature token.
Whenever a creature you control attacks, you
may have it become a copy of a creature you
own in exile until end of turn. When you do,
untap that creature and it perpetually gains
"This creature has +1/+1 and is a white, blue,
and black Spirit Warrior in addition to its other
colors and types."