Illusioners one time spawn

Illusioners have a one time spawn at the top of Pillager outposts.

The outpost kind of looks like a mages tower, and the Illusioner could finally have a use. It could also drop some sort of arrow or potion that isn't usually obtainable, such as ones that can't currently be brewed or obtained in survival. Perhaps blindness or nausea would be useful if it had an effect on mobs. Some tweaks could also be applied to it's behavior to mimic the Illusioner from Minecraft Dungeons, being the ability to teleport, the duplicates firing arrows, and firing explosive arrows/firework arrows.