Roilmage's Trick [Battle for Zendikar]

Set: Battle for Zendikar Type: Instant Rarity: Common Cost: {3}{U} Converge — Creatures your opponents control get -X/-0 until end of turn, where X is the number of colors of mana spent to cast this spell.Draw a card. Weather on Zendikar is unpredictable—unless you're the one telling it what to do.