Featherfall Potion

This is not simply a slow descent. Holding up nearly stops you, holding down drops you at full speed, and letting go sits you in between. Three fall rates you can switch between in midair is much closer to a hover than to a feather. Check which control scheme you are on in the settings before a boss, because the click based option behaves differently from the hold based one.

Wings give you lift and a hover once the meter empties. This gives you fine control on the way down without spending any flight time. Together you cover more vertical ground per second of flight, and you can hold altitude between flights instead of sinking. For anyone without a flying mount it is the cheapest mobility upgrade available.

The fall protection applies even at normal falling speed and even while stoned, which nothing else except the Djinn's Curse manages. The slow drop makes it easy to lay platforms or track underneath yourself as you go, and easy to spot a pressure plate before you land on it. There is also a launch trick: grapple to something overhead, hold up, and let go of the hook early, and you can be flung high enough to reach a floating island with nothing else equipped.

The ingredients come off harpies, so the moment you can clear a sky island comfortably you can brew more of these than you will ever drink. Treat it as an always on buff, not something to ration.