Appearing to be in his middle years, he is tall and handsome with dark deep set eyes and dark hair.
In "The Wheel of Time Companion" his level of strength in the One Power is described as ++3, making him one of the most powerful channelers ever, putting him above all female channelers in the series, but below most of the male Forsaken. The only male member of the Forsaken who was known to be weaker in the Power than he was is Be'lal, but despite ranking seventh amongst them in terms of power, he was always described as having been amongst the weakest of the Forsaken. This is likely due to the fact that he appeared to have very few talents besides his extraordinary skill as a musician, whereas other, weaker members of the Forsaken offset their lesser channeling capabilities with other abilities.
His channeling abilities are never fully revealed in the series, as he is partially shielded by Lanfear for most of his tenure. Asmodean was considered weak in the One Power by the other Forsaken, but his place among the Forsaken in the first place (the most powerful channelers on the side of the Shadow at the time) suggests he was still extremely powerful by most standards, even if he is among the weakest of them. He was able to hold his own against Rand al'Thor during their battle in Rhuidean, and although Rand had not yet attained his full potential by a considerable margin he was still very powerful. He claimed to have had little skill with Healing or in working with the weather.
Asmodean was born in the port town of Shorelle, and his mother was an Aes Sedai. While he showed great promise as a musician during his childhood, it seems that he never fulfilled his potential. Despite his fame as a composer and the prestige of earning a third name (presumably due to his musical talents), Asmodean felt that he did not get the credit he deserved.
Asmodean turned to the Shadow during the Collapse for the opportunity to take revenge on every musician said to be better than him. Asmodean was also lured by the promise of immortality, which would allow him an eternity to attain musical perfection, and just as importantly the recognition of his talents that he sought.
During the War of the Shadow Asmodean served the Shadow as a capable, if not exceptional, governor. While his administrations were not particularly brutal compared to the other Forsaken, Asmodean was noted for one signature atrocity: any musician or artist whose work he had disapproved of before the war - especially those he considered his former rivals - was blinded and/or otherwise maimed. There was no other torture involved; Asmodean's victims were simply rendered incapable of practicing their art and then released. He is also known for having severed his Aes Sedai mother and given her to the Myrddraal for sport.
Along with the other twelve most powerful of the Chosen, he attended a meeting with the Dark One in Shayol Ghul on the fateful day that Lews Therin Telamon and the Hundred Companions sealed the Bore, trapping the Chosen in a dreamless sleep for 3,000 years. Several Chosen close to the edge of the seal experienced dreams, usually nightmares.
After his release from the Bore, Asmodean allied with Lanfear. She disguised as a peddler and he as a gleeman called Jasin Natael, they traveled with a train of Darkfriend peddlers in the Aiel Waste to follow Rand al'Thor and Taardad Aiel to Alcair Dal.
As Jasin NatealEdit
He has dark, deep-set eyes. Taller than most, somewhere in his middle years and attractive, Jasin Nateal fits his own true description as Asmodean pretty closely. He frequently cocks his head when speaking with a person, looking at him or her sideways.
Within the Waste Edit
During this time, he approached Mat Cauthon to learn more about the reincarnated Dragon, pretending to research for composing the tales of the Dragon Reborn. He later creates counterfeit dragons on Couladin's forearms to create enough chaos to allow him to reach Rhuidean unnoticed so he can obtain the ter'angreal used to access the male Choedan Kal.
Warned by Lanfear, Rand followed him to Rhuidean. They battled, both drawing on saidin through the sa'angreal, but Rand won by drawing a fractional amount extra through the fat man angreal. Rand severed Asmodean's link to the Dark One, leaving him exposed to the taint on saidin. Lanfear then shielded Asmodean so that he could only channel "a trickle", and instructed him to train Rand in the Power (ironically, Asmodean's attempt on Rand's life at Rhuidean eventually kept Rand from being killed by ignorance of the Power).
With the Dragon RebornEdit
Continuing to disguise himself as Jasin Natael, he trained Rand diligently and without signs of treachery, and as time passed it seemed he might genuinely want to join the side of the Light. Asmodean was known among the Forsaken for his habit of throwing his lot in with whomever he thought would win, which perhaps explains why the Forsaken did not attempt to rescue him.
While crossing over the Spine of the World near Kinslayer's dagger, Asmodean lamented about his home city of Shorelle as they passed what looked like crumbling docks in the high passes of the Spine of the World. Because he was sealed in the Bore before the Breaking of the World, it is believed that Asmodean has no known knowledge of precisely where Shorelle would have been located.
During the skirmish with Rahvin in Caemlyn, Rahvin killed Asmodean, Mat Cauthon and Aviendha amongst others. When Rand finally killed Rahvin using a very powerful blast of balefire, he undid the Forsaken's earlier attack, bringing Asmodean, Mat and Aviendha back to life.
However, for Asmodean, this was only a temporary respite. In search of refreshments in a cupboard, he runs into someone he recognizes and is killed immediately. The identity of this murderer is left unknown for a long time. It is finally revealed by Shaidar Haran when he blames Graendal for the destruction of three of the Chosen. While he mentioned only Mesaana, it is clear she is also responsible for the deaths of Aran'gar and Asmodean.
Asmodeus is a king of demons in the Book of Tobit. He is often referred to being one of the princes of Hell or the ruler of the nine levels of Hell. Asmodeus is also the embodiment of the sin of lust.