The Banshee is a mob that would spawn in a new structure called "The Tangle Maze" ( The Tangle Maze (A new End Structure) ) which is located in a new End biome called The Tangle, Link Here: The Tangle (New end Biome)
The Banshee has the feel of a shulker in the sense that is has a light purple shell, with an orb inside. But this is NO SHULKER! This mob is rectangular in shape. It opens like an ender dragon's mouth and has an ender pearl colored orb in the back of its "mouth" so to speak. it stands on three legs and kind of resembles a turret. When it attacks it opens and emits a very load screeching sound similar to a very angry enderman shooting these soundwave-like projectiles that deal rapid damage.
Using an item you'd get from "The Tangle Maze" you can tame it. Once tamed you can walk into it allowing it to ride on your shoulder acting like an auto turret.
Remember to Vote if you'd like to see The Banshee added in the Fan Update!