A massive undead monster with a hunched posture

A massive undead monster with a hunched posture, oversized asymmetrical arms, huge ivory claws, a dark mossy-green and rusty-red body, ragged dark trousers, and a horrifying face with a glowing magenta eye and a mouth full of large blocky teeth. Its body is covered in glowing orange jack-o'-lantern growths, tiny luminous mushrooms, thorny vines, decayed armor pieces and floating Halloween particles. Include a bright orange pumpkin-shaped core embedded in its chest, emitting magical flames and pixelated sparks. Add small pumpkins growing on its shoulders and back.