Here we have Epitaphe showing off his left arm markings as well as his stomach actually being a second, larger mouth with its own tongue and saliva, but no teeth and no way to actually swallow. His stomach can hold victims, and its purpose is to drain and/or regress them to an earlier state, whether by age or by form, by siphoning their quintessence. As an example, if a vaporeon were to be swallowed by his stomach and held in there long enough, it might come out as an eevee.

Yes, his left and right arms have different markings. Yes, each set of markings (arms, face, and stomach) represent different magics. And yes, just because yes.

Bust I got from ( anonymous ).