Surgespanner

The bounce trigger keys off this Merfolk becoming tapped, not off attacking or activating an ability, so the engine fires whenever you can manufacture a tapping event. Crew a vehicle, convoke a spell, tap it to a Springleaf Drum or a Voyaging Satyr effect, hand it an untapper, and each tap converts into a repeatable : return target permanent to its owner's hand. The body never has to enter combat to matter; it can sit back as an open-ended Boomerang dispenser, resetting a problematic permanent every time something taps it for value. That is the friction baked into the rate: a 2/2 for four mana is unremarkable, and the bounce is gated twice, behind a tapping event you have to engineer and behind a separate payment, so the loop is never handed to you for free. Left to swing on its own, it is a slow, mana-hungry pseudo-evasion threat that nudges blockers and ramp out of the way one attack at a time. Married to any cheap repeatable tap, it tightens into a soft lock: every untap step, another permanent goes home. Everything about how it plays hinges on whether you can divorce "becomes tapped" from "attacks," and the engines builders reach for around it exist precisely to break that link.