Cool!!
Looks like a mix of Anubis ( the egiptian god of the dead) and the ebf2 Giant worm.
I luv your artworks! How many weapons there will be in the game? U could make this boss like the robot in ebf2 , cause he could regenerate himself. Like : if you destroy the under monster the other, that looks like anubis ,could become a normal body and gain the under monster after 6 turns. N if the monster that looks like Anubis get killed he does not become regenerated,but the under monster become a mutant giant golem! :)