Samael was the Archdemon of Hell during the time of The First Void Insurrection and the aftermath of the Insurrection, the Nephilim Purge. He is an immortal demon, and was both the military commander as well as the King of the Demons in Hell. During his rule, he was feared and respected equally. He led the charge against the Void Avatar on behalf of the Demons.
In the aftermath of the First Void Insurrection, Samael was a stout supporter of the systematic eradication of the Nephilim race. He was considered a formidable opponent, even for a Nephilim, and he was even able to best a Nephilim in single combat. He lead the Demons in the hunt for the remaining Nephilim. In the final stages of the purge, he became locked in combat with the Nephilim Tyrael. Though it was a close fight, Samael was ultimately defeated.
Instead of being destroyed by Tyrael, he was locked deep within the reaches of Hell inside a prison made of Void. During this battle, Tyrael injured Samael with a Void-type spell, causing the Void to infect him. In the thousands of years that have passed since the Nephilim Purge, Samael has become attuned to the power of the Void that built up inside and around him, being able to wield it for his own, though he isn't able to use this to his advantage, as the Void prison prevents him from escaping. With that knowledge, Samael has lied dormant in his prison ever since, to this day.
He is kept under watch by the new Archdemon of Hell, Rozalin, and a covenant of Soulmagi, who keep the magical boundaries in check and to keep the Void contained within the prison. The Nephilim Amanda Hathaway keeps watch over Samael from time to time, acting as Warden.
Samael's Void Prison was shattered once the new Void Avatar Yamato Haseo brought a visit to Hell. After instilling the young Void Avatar with transferred knowledge, he saw fit to use the small timeframe to escape from his prison, yet with the combined efforts of the Void Avatar, Amanda, Rozalin and the Hellguard he was locked away once more. This time, the Void Prison was stronger than ever before, not only renewing Tyrael's old Void Prison but strengthening it with Yamato's own Void. What the current effects are on Samael after his temporary burst of freedom are unclear.
Samael is best described as a towering behemoth compared to his kin. His flesh colours in shades of ashen-grey. Four ram horns curl out of his head, two straight up backwards and two curling down and outwards. Covering his overly muscular torso is a set of dark iron armour. His legplates cut off at the carpal bone, leaving room for his cloven, black hooves. His gauntlets are reinforced, thickened with layering of iron sheets, protecting his sharp, claw-like hands. The breastplate is opened on the back, granting his wing muscles space to move within, as well as leaving room for his tail.
His demonic assets, such as his hooves and wings, have darkened, bearing a black colour after the Void tore away at his within his prison. The outlines of his wings, or the tips of his horns, or even his fiery eyes might glint with a shimmer of deep purple, like a dim flame from an ember.
Samael is considered the most powerful Archdemon to have wandered Creation. A formidable warrior to reckon with, capable of setting entire battefields ablaze with a swipe of his hand as he descends into the fiery fray, his Warglaives at the ready. Such is only to be expected from the Supreme Commander and uncontested King of Hell.
After his imprisonment, his magical abilities shifted towards the sole power of Void, since his entire being was infected by Void. In his solitude, he has attuned to the power of Void, though there are still levels of Void exposure which he cannot withstand, like that of a Void Avatar. Over the course of his imprisonment, he has perfected his use of the Void, though only for practical skills. He can't use any other form of Void unless his boundaries are lifted.