Glimmerbell

A 1/3 flyer that can stand up again after it swings is a real body: block the turn you attacked, so long as you hold two mana for the untap. But the self-untap ability reads like an engine and mostly isn't one, and the seam that trips up build-arounds is which direction the value flows. Untapping itself does nothing on its own account; the power of 1 caps the offense on purpose, and the repeated taxes every activation so no loop comes free. What the jellyfish actually wants is a reason to tap. Hand it an aura or equipment that grants a tap ability, or park it beside any effect that pays out when a creature becomes tapped, and the untap clause turns into a resetter: fire the tap payoff, spend to straighten back up, repeat every turn without ever spending the body itself. The untap is the second half of a two-part machine whose first half lives on another card. Absent that partner, this is a serviceable defensive flyer with a mana sink stapled on, and the mana sink is doing the least interesting work available to it. The ceiling belongs entirely to whatever tap-triggered payoff you point it at; Glimmerbell supplies only the resilience to keep pulling the trigger.