Undisguised and unveiled:
Asteroth is lithe framed and generally black robed trimmed in scarlet and gold.  His delicate porcelain features betray his First Born blood while his pale, platinum hair, generally cropped short, frames a fierce and exotic visage that gives him the look of a predator.  Asteroth's most startling feature are his dazzling amethyst eyes which seem to notice, process and weigh anything and everything they fall upon.

Disguised:
Asteroth appears like his Undisguised and unveiled form except he appears more Human than Elven and he is  a more idealized version of himself (a little taller, a little more handsome, whiter teeth, etc...).

Veiled (what he looks like (99% of the time under the Disguise Self effect):
A black robed, cloaked and cowled figure wearing a shadowy veil.