Nature's Rhythm
Tarkir: Dragonstorm · 150
Type: Sorcery
Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.
Harmonize 
(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.)
(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.)