NodeCraft
A Pixie Plate is a held item that raises the power of the holder's Fairy-type moves by 20%. When held by Arceus, its typing and its signature move Judgment become Fairy-type, and it and any Fairy-type move receive the power boost.
It can be obtained as a drop from Mega boss Pokémon.
Trivia
The Pixie Plate used to have a crafting recipe. This recipe no longer works.
