I’m trying to blend the silver, shiny wall of the monster into the purple, flat material of the wall but whatever I try it won’t produce a smooth blend.
add an empty behind the wall where the head is,
use it as the object in the ‘map input’ for a blend texture in your material. use that material for the head and walls.
then when you want the head to appear move the empty towards the wall and maybe scale it up. the wall should turn pink in the area close to the empty.