Asmoday as he appears in the “Stephenson” Ars Goetia, and as a commissioned piece (“The Demon Regent Asmodeus”, 2014).
You can see the Seal (Sigil, Lamen) of the Spirit in both images. The latter places the three heads on a geometric shape, as King Asmoday doth teach the arts of Arithmetic, Geometry and Astronomy.
The ring that Asmodeus holds is the Ring of Virtues, and he governs over 72 legions of inferior spirits.
It is said that he giveth the Helmet of Hades to the aspirant, which doth make one invisible to the other Spirits, so that thou canst retrieve the treasure (Terma) from its hidden location.
Occult Aspects 