What's the deal with Minecraft: Story Mode's Wither Storm?

Almost everything in Minecraft: Story Mode exists in vanilla Minecraft or resource packs - except the Wither Storm.

Minecraft: Story Mode from Telltale Games set for Season 2

Withered Symbiont, Minecraft Story Mode Fanon Wiki

30cm Wither Storm Model Plush Doll Minecraft Story Mode Stuffed

Minecraft Story Mode episode 3 review

Minecraft: Story Mode gets stuck between 'A Block and a Hard Place

Minecraft Story Episode 4: A Block and Hard Place review

LF Minecraft story mode wither Storm

Who gave the witherstorm such a fire theme #minecraftstorymode

I made the Wither Storm from Minecraft Story Mode using commands

if only the wither storm had deeper lore instead of just wither