Nature's Rhythm (TDM-150) - Tarkir: Dragonstorm

Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Harmonize XGGGG (You may cast this card from your graveyard for its harmonize cost. You may tap a creature you control to reduce that cost by an amount of generic mana equal to its power. Then exile this spell.)