The Flügel Tiara is a bauble added by Botania. Its entry in the Lexica Botania is initially hidden until the player acquires Elven Knowledge. When worn, the player can fly as if they were in Creative mode by consuming Mana from a carried Mana Tablet, at a rate of 70 per tick or 1400 per second. When in flight, white sparks trail behind the player.
To equip the Flügel Tiara, press B (by default) to open the Baubles inventory GUI to equip it in the Amulet slot.
This item, as well as the quote in the Lexica Botania (right under recipe) are a reference to the anime/light novel No Game No Life.