Addwaitya

Adwaita (Charmcaster pronounced it add-way-cha, while he pronounced it add-wait-yah) is a Geochelone Aerio that mastered magic thousands of years ago. He's an evil mystic being considered as the most powerful sorcerer in the universe. He was slightly mentioned and introduced in Where the Magic Happens and is responsible for the death of Spellbinder, Charmcaster's father.

Appearance
Adwaita is a turtle-like creature with pink mana fire-like energy surrounding his head. Following the loss of the Alpha Rune (and most of his mystical energies), the flames vanish.

Backstory
Adwaita, at some point, got his hands on the Alpha Rune, an exceedingly powerful magical mystic item (which was actually a piece of the Map of Infinity in disguise) and reached the interdimensional world of Ledgerdomain. He got corrupted by the immense power the artifact possesses. The inhabitants of Ledgerdomain, though very powerful sorcerers and sorceresses, were unable to defeat him, and their leader, Spellbinder, was forced to send his brother, Hex, and his daughter, Charmcaster, to Earth in order to keep them safe. While he did that, Adwaita murdered him and took control of Ledgerdomain as a ruthless dictator. He had also enslaved most of the people of Ledgerdomain to do his bidding.

Ben 10: Ultimate Alien
Adwaita was first seen in Where the Magic Happens, when Ultimate Aggregor reached Ledgerdomain in order to get his hand on the Alpha Rune. Chasing him, Ben, Kevin and Gwen were forced to ask for Charmcaster's help in order to reach the Ledgerdomain. When the group arrived, Adwaita immediately felt their presence and enraged by the intrusion, attacked them. Adwaita also used Spellbinder's voice to encourage Charmcaster to fall to her death (but the team stopped Charmcaster from doing so). When they got to Adwaita's citadel, a Palorfayg attacked them and it died after falling off the edge of the land. After a feral fight, Adwaita was surprised by an attack from Ultimate Humungousaur, allowing Ultimate Aggregor to knock him out with a sneak attack and escape with the Alpha Rune. Ledgerdomain then started falling apart and Charmcaster, seeing Adwaita weakened, chose to stay behind to fight him and save her people.

It is shown in The Enemy of My Frenemy he was so corrupt with power he became insane and is not in the right mind in the end after his overthrow and lost of the Alpha Rune. And of course he has a guard his name is Palorfang.

Powers and Abilities
Adwaita is shown to be incredibly strong when he has the Alpha-Rune. Capable of doing spells without saying them, he easily defeated Gwen, Charmcaster and Kevin. He was even capable of fighting Ben as Ultimate Humungousaur.

Without the Alpha Rune he still is capable of doing spells just like any normal magician, but he was shown to be no match against Charmcaster when she held the Alpha-Rune.

Ben 10: Ultimate Alien

 * Where the Magic Happens (First appearance)
 * The Enemy of My Frenemy
 * The Ultimate Enemy: Part 2 (Flashback)

Trivia

 * According to Dwayne, Adwaita retains his normal Geochelone Aerio powers, even though he lacks holes on his torso.
 * Adwaita is named after a tortoise from an Indian Zoo that lived to be 255 years old and is a Sanskrit word 'advitya' that means "something which is second to none"
 * Adwaita was a revered philosopher and mystic of his species, whom appeared to achieve godhood. According to Dwayne, no one knows that he became corrupt.
 * His appearance and place of residence is reminiscent of the extradimensional tyrant Dormammu.