Merciless Harlequin

Freerunning is a combat-conditional discount: land a hit this turn and the payment drops from three mana to two. That turns a modest cantrip body into a reward for having already done the aggressive thing, which is the design tension worth watching. The enters-trigger is the Phyrexian Rager package in a cheaper shell: a card drawn, a life paid, a 2/1 that pressures for a turn and then dies to almost anything. Because the discount keys off combat damage, this is a natural second-main-phase play, a way to spend the mana you deliberately held through your attack step and convert a successful swing into a fresh body that can attack again next turn, rather than a turn-three curve filler. The two effects are decoupled, which is the subtlety: the reduced cost rewards the swing, while the enters cantrip fires no matter how you paid or whether you attacked at all, so the card is playable at full price on a stalled board and simply cheaper when the beatdown is already underway. The life loss keeps the engine honest: recasting it through blink or reanimation is not free, and the card asks a deck already leaning on Assassin damage to absorb the drain as the price of keeping cards flowing. It is a keyword built to reward decks that are already attacking, stapled to a body that pays out regardless.