Birthing Ritual Aetherdrift Spend this mana only to

Spend this mana only to cast creature spells with mana value 4 or greater or creature spells with {X} in their mana costs

gain control of target creature an opponent controls until end of turn

(It's an artifact with "{T}

(You may cast a spell for its freerunning cost if you dealt combat damage to a player this turn with an Assassin or commander

Birthing Ritual Aetherdrift Spend this mana only toAt the beginning of your end step, if you control a creature, look at the top seven cards of your library. Then you may sacrifice a creature. If you do, you may put a creature card with mana value X or less from among those cards onto the battlefield, where X is 1 plus the sacrificed creature's mana value. Put the rest on the bottom of your library in a random order.