Tira, Curse of Stonehammer

At the beginning of each player's upkeep you may
pay {2}. If you do, create a Curse Aura
enchantment token with "This creature gets
-1/-1." attached to a target creature that player controls.
Whenever a creature with a Curse aura attached
to it dies, return it to the battlefield with a -1/-1 counter under your control. Search your library
for a Curse Aura enchantment and attach it to
the creature's previous controller. Shuffle your library.