Kurayami, Spirit Thief

At the end of your turn, each opponent loses life
equal to the number of permanents they control
but don't own. If they lost 5 or more life this
way, they must sacrifice a creature they own. You
then gain life equal to the number of permanents
you control but don't own.
Sacrifice X permanents you control but don't
own and discard Y cards that you don't own,
where X+Y must equal 13: Transform
Kurayami, Spirit Thief.