Ruby, Daring Tracker

Two-drop mana dorks that fix two colors are old hat, but this one comes off the bench already able to attack. The tap ability is the tame half of the card: it accelerates and fixes like any Gruul rock, and on turn two that is all it does, since a 1/2 swinging into an open board is a wasted card. Haste is where the design turns, because it lets Ruby matter the moment she arrives. Cast her later in the game, when a real threat is already down, and the trigger fires the turn she enters: attack alongside a creature with power four or greater and the 1/2 immediately becomes a 3/4 that trades up or draws removal off your bigger board. That is the whole logic. Haste keeps a mana creature from being a dead draw once the ramp phase is over, because she can contribute to the attack the same turn she hits play rather than waiting a rotation to shake off summoning sickness. The four-power condition is generous rather than clever: it is a low bar for the kind of aggressive green-red board this deck is built to make, so the buff switches on more or less by default whenever the strategy is working. What balances the card is the body underneath, a 1/2 that connects for nothing on its own and needs a genuine threat standing next to it before any of the ambition pays out.