Inverted Warding Bond

Enchant player other than yourself.
As Inverted Warding Bond enters the
battlefield, the target may pay {2}. If they
do, sacrifice Inverted Warding Bond.
Spells targeting you that are not controlled by
you or enchanted player cost {1} more to play.
When you would take damage, you and
enchanted player instead take half as much
damage (rounded down).