Harpy armor is a mid-game armor set. It can be crafted using 28 silk and 23 feathers. Crafting all headpieces requires 44 silk and 31 feathers. Its set bonus mimics the glide of wings and negates all fall damage if you are gliding downward. The increased jump height also mimics that of a shiny red balloon accessory.
This armor set is an extremely useful mobility set, allowing you to jump high, glide down slowly and negate all fall damage (when gliding)
It essentially acts as a permanent Featherfall potion and a free Shiny Red Balloon accessory.