Minecraft wiki entry for ED, associated text: Entity data
Tags common to all entities[show]
Tags common to all mobs[show]
 AX: The phantom, when not actively attacking, attempts to circle around X,Y,Z = AX, AY, AZ. Appears to reset to a point above the target player every time the phantom flies up after a swoop. Set to spawn location if not specified.
 AY: See AX.
 AZ: See AX.
 Size: The size of the phantom. Ranges from 0 to 64, similar to slimes. Unlike slimes, phantoms always have a constant 20 × 10 HP, and deal 6+Size damage. Naturally spawned phantoms are always size 0.