Avizoa

The free activation cost is the trick here, and it teaches you the whole card. Pumping to 4/4 in the air costs no mana, which means the body can attack and threaten well above its printed size on any given turn. The price is paid in time: each pump makes you skip your next untap step, which freezes your lands, your other creatures, and the jellyfish itself. So the real resource being spent is tempo, not mana, and the once-per-turn clause keeps the engine from spiraling. The design question it poses is one of pacing: do you commit to a big swing now and accept a turn of paralysis, or hold the pump and keep your mana open? Because the cost is paid on your following untap rather than up front, you can sometimes sequence around it (pump once blockers are declared, or on a turn you do not need your lands anyway), which is where the card's small skill ceiling lives. It is a flier that lets you trade your clock against your board's mobility, a quiet study in how an activated ability can be balanced entirely through timing rather than price.