@Boomburst it looks like he changes his blood/limps into mana, recall it back to his body and then have it rebuild itself back on his body.... so if u eat his limps/body he can't regenerate.
@Zieg Think he only has a few kilos in his body which he uses to produce a skin over himself. Mimicking a normal metal slime. I don't think he can create orichalcum out of nothing considering it is magic resistant