Shang-Chi, Master of Kung Fu

Green rarely builds around the tap-symbol creature: the pinger, the mana dork, the sacrifice engine, the tapper whose value lives in a costed activation rather than a swing. This warrior points at that overlooked axis twice. The first clause lets you activate creatures' abilities as though they had haste, which matters specifically for the abilities summoning sickness would otherwise gate, chiefly the tap and untap-symbol activations that a freshly cast creature normally cannot fire until its next turn. Cast the engine, ignore the sickness, tap it the same turn. The second clause is a battery: two mana of one color, ringfenced so it only pays for activated abilities of creature sources. That restriction is the whole shape of the design. The mana cannot cast a spell, cannot power equipment or planeswalker loyalty, cannot touch anything that is not an ability on a creature body, but within that lane it is broad. It funds any creature's activated ability, not merely the ones the haste clause unlocked, and plenty of those abilities never cared about summoning sickness or cost no mana at all. The two halves overlap without being identical: one removes the timing tax on tap abilities, the other bankrolls the expensive ones. Together they reward a board of activations over a board of attackers, a design lane green seldom gets, carried by a 2/2 whose payoff is meant to come from what it enables rather than what it swings for.