Tanka, World Creator

Partner with any Legendary creature in your library
Exert this creature and the creature it is partnered with: return a permanent from a graveyard to the battlefield under your control. If it was returned from an opponents graveyard, put
a -1/-1 counter on it at the beginning of your upkeep; if it would die, exile it instead
{6}, Exile this creature: Return all permanents from graveyards to the battlefield under their owners control