Caastumi is a demon of invisibility associated with an invisibility spell in the Clavicula Salomonis. Castumi serves Almias, the demonic Master of Invisibility. He is also associated with invisibility spells found in Mathers’ Sacred Magic of Abramelin the Mage. A.G.H.
Belanger, Michelle. The Dictionary of Demon: Names of the Damneds. Llewellen Publications. 2010. ebook.