Praeparatio

{x}{t}: Search your library for X instant or sorcery cards, reveal them and put them into your hand. You may cast one of those instant or sorcery spells with converted mana cost X or less where X is the amount of mana used to activate Praeparatio without paying that spells mana cost.

{x}{t}: Target creature gets +X/X until end of turn.

{x}{t}: Target Creature gets -X/X until end of turn.

{x}{t}: target opponent exile the top X cards from their library.