The Speed Demon
Black has always been willing to sell life for cards; the design question is how much, and how fast. This is Yawgmoth's Bargain wearing a body, but with a governor bolted onto the throttle: the draw meters to your speed counter, so it never opens the floodgates the way the truly broken life-for-cards effects did. Speed climbs by one at most each turn, and it climbs only on the turns you are draining life out of an opponent, so the card that ostensibly rewards aggression demands you already be ahead in the damage race before it pays you fully. A static "draw four, lose four" every end step would be a two-turn clock on yourself; the forced ramp from one buys you turns to bank cards before the life payment gets steep. The 5/5 flying trample body does the work of getting the counter off the ground, since evasive beats reliably connect and push the meter up. Both halves feed the same loop: the attack raises your speed, the speed refills your hand, the refilled hand keeps the attacks coming. It is a self-propelling value creature that punishes you for stalling out, which is exactly the tension the mechanic was built to express: reward the deck that keeps the pressure on, tax the deck that idles.
