Malenia, Blade of Miquella

Doublestrike, Vigilance, Deathouch, Haste.

During your opponents declare blockers step,
creatures you control have "Whenever this creature
deals damage, you gain life equal to that creature's
toughness".
If Malenia, Blade of Miquella would leave the battlefield, instead, search your library, hand,
graveyard can/or cards you own in exile for a card
named "Malenia's Great Rune" and put it onto the battlefield.