Giggling Skitterspike

The clever part is the target clause. Most punisher creatures pose a question to an opponent: pay the toll, or accept the consequence. This one deletes the choice, because the damage trigger fires on your action or theirs. When it attacks, it burns each opponent. When it blocks, it burns them. And the instant anyone aims a spell at it, it burns them again, which converts the reflexive answer to a threatening creature (kill it) into a cost the caster eats just to interact. Indestructible seals that last mode: it shrugs off most of what would remove it, so the punish resolves and the body stays put. Monstrosity is the escalation switch. As a 1/1 the damage is a pinprick; the ability stacks five counters that scale every future trigger, since the damage tracks its power and monstrosity permanently lifts that number. What results is a tight feedback loop: pay once to enlarge it, and each subsequent attack, block, and hostile spell lands harder than the last. It belongs to the family of "hurt-to-touch" threats, but where those usually restrict the pain to a single trigger type, this one collects rent across nearly every avenue an opponent has for engaging with a creature at all: swinging into it, blocking it, or trying to answer it. The only clean way to deal with it is to leave it alone.