Xarnathyllyn, the Luck Bringer

Trample

When this creature enters the battlefield, search your library for any number of permanents with total mana cost equal to the amount of mana spent to cast this creature, then put a random one onto the battlefield and the rest on the bottom of your library in a random order.

{x}{b}{r}, Sacrifice target permanent you control: Reveal the top X cards of your library and put one with converted mana cost less than the target's onto the battlefield and the rest on the bottom of your library.