Fia, Deathbed Companion

Deathtouch, lifelink
Whenever you cast another legendary creature,
you may pay {w/b}. When you do, that creature gets
+1/-1 until the beginning of your next upkeep.
At the beginning of your end step, you may exile target legendary creature from your graveyard.
When you do, shuffle that card into your library
at the beginning of your next end step.