Sharkron Balloon

It merges a balloon and a bottle, so you get a taller standing jump plus a jump in midair. The midair half is one of the weakest available: only the cloud version goes lower. On paper that reads badly. In practice the height is not what you are buying.

Fire the second jump and it kick starts your wings, so you end the climb higher than the wings would have taken you alone, with the raised base jump sitting underneath all of it. Timed just before you land, the same jump erases fall damage. Both of those work regardless of how tall the jump itself is.

Both halves came out of the ocean and neither performs in it. Jump height drops while you are submerged, which is worth remembering before you build an arena at sea level.

If fall damage is the reason you keep hesitating, a Lucky Horseshoe upgrades this in place rather than costing you a second slot.