Hercules, Olympian Hero
Two counter engines pointed at the same body, and both of them turn incoming damage into a reason to keep swinging. Attacking hands him a counter every combat plus indestructibility for the turn, so blocking with anything short of exile or bounce just feeds him. The second trigger rewards a specific kind of recklessness: because he only banks the counters if he survives, and because the swing has already made him indestructible, the intended loop is to attack, shrug off a hit that would otherwise be lethal, and pocket that damage as permanent size. The counters scale to the damage dealt, so it is the big blocker or the burn spell aimed at his face that pays out, not the one-power chump: soak a five-damage swing while indestructible and he keeps all five. That inversion (damage as growth rather than depletion) is the design's whole personality: most creatures shrink under pressure, and this one is built to be shot at. Worth noting is the "first time each turn" clause, which caps the payout to a single damage event and keeps one mass-combat from spiraling out of control. What that leaves is a threat that punishes the two most instinctive answers to a growing attacker (block it, burn it) and forces the opponent to find a third. A demigod who gets stronger the harder you hit him is exactly the flavor the mechanics are chasing.
