Alright so my two rare drop suggestions are:

Impostercube Helm (dropped by Impostercube) - A jelly helm but with the hair, mustache, and pipe!

Soul Helm (Dropped by Soul Jelly) - A Soul-like skull as seen in moorcraft, phantoms, firestorm, and inside the soul jelly itself. Perhaps a upgraded version to either have a light glowing aura added, or a red aura to take on the look of a Phantom

Well these are my suggestions, I hope you like them and if these became new items I would be on hunt for them!