King Harald's Revenge

Two effects that usually live on separate cards, welded together at a price that only pays off in a specific board state. The pump scales off your whole creature count, so the buff is worthless in a vacuum and enormous once you have committed a wide board; the card is written for the go-wide green deck that already wants to alpha strike and just needs the math to break through. Trample handles the chump-block, but the "must be blocked if able" clause is the sharper half of the design: it forces a defender to eat the swing rather than sit back, dragging a blocker into a fight it will lose. That combination (grow one attacker large, force a block, then punch the overflow across everything else) makes this less a combat trick than a swing-ending finisher. The cost is that it does nothing early and everything late, a sorcery-speed reward for having already done the work of flooding the board, which is exactly the deck it was built to close out.