Floodpits Drowner

Tapping a creature is soft removal on a timer; the stun counter is what turns the timer into a lock, because the tapped creature will not untap on its owner's next turn. The enter trigger stalls a blocker or attacker for a beat, but the counter is doing double duty: it also marks the creature as a legal target for the activation, which folds both the marked permanent and this Merfolk into their owners' libraries. That is not destruction, so it slides under indestructibility, regeneration, and death triggers, and it dodges graveyard recursion by burying the threat somewhere in a shuffled deck rather than a pile anyone can raid. The catch keeps it a genuine trade: the shuffle sends this body away too, so each activation is a real one-for-one, a two-mana creature swapped for an opponent's (often far larger) permanent and gone from play. Reload has to come from a fresh copy or a fresh draw; there is no loop here. Flash and vigilance handle the timing from both sides. You can hold it as an ambush, flash it in to stun an attacker before combat damage, or attack with it and, because vigilance leaves it untapped, still keep the activation available as a follow-up threat. The design sits in the seam between tempo creature and answer, and the stun counter is the connective tissue that lets one card play either role without forcing the choice at the moment you cast it.