Mordred, the Wicked King is a custom champion in League of Legends.
A Pit Lord champion similar from Heroes of Might and Magic (V and VI). (God I love these Inferno creatures, and their Vorpal Sword.)
If angelic race like Kayle and Morgana exist, why not a demonic champion?
The name Mordred is based from Arthurian Legend, where Mordred is the final foe for King Arthur "Pendragon", his uncle/father. Mordred dies, but he manages to deliver a fatal blow to King Arthur, who dies as well.
In LoL story (fan-fiction), before the rebellion, Morgana had a child, unknown to everyone. But their leader known as "Pendragon, the Redeemer", decided to gather up babies including Mordred, after hearing a prophecy from the Fates he reclaimed, a child born to the day so called "evil" were banished from their homeland, as Mordred was one of them, will destroy Pendragon. Pendragon, along with his angelic warriors took babies into a ship, to crash outside of their homeland. Morgana distraught for the loss of Mordred, went insane and saw her kin and their act of justice as tyranny. However, no one knew that Mordred survived the shipwreck, which landed in the land of opposite race, where demonic beings lives.
What he did from there, only Mordred knows...
Other Champions that I've done
Mordred, the Wicked King