Skullbriar

Skullbriar the Walking Grave is a legendary zombie elemental from an unspecified plane.

This undead monstrosity was formed when a necromancer and an elementalist entered into a grim pact. The two mages wove their different magics together in an overgrown cemetery, thinking it would bring them eternal life. Instead, it fused them together into Skullbriar, the relentless, restless elemental of death.