Diagon is believed to have visited Earth many years ago and gave humans advanced technology. He is also believed to have sworn to come back to Earth to bring the "Golden Age". He claimed he would bring alien technology so that Earth will not have war, nor disease, just peace. Vilgax was mistaken for, and pretended to be Diagon.
Diagon is in fact an extra-dimensional demonic entity who tried to invade this dimension with the help of his Lucubra army during Earth's medieval era. He was banished back to his dimension when Sir George defeated him by cutting out his heart with Ascalon, a powerful weapon given to him by Azmuth nearly one thousand years ago.
Powers and Stats
Tier: At least 3-A
Name: Diagon, The Great One, The Dragon, The Old One, The Knowledge Bringer, Diagon the Destroyer
Origin: Ben 10
Age: At least 1700
Classification: Extra-dimensional demon
Powers and Abilities: Superhuman Physical Characteristics, Immortality (Type 1), Fire Manipulation, Shapeshifting, Flight, Mind Control and Transmutation (Transformed every living being on Earth into one of his minions while still sealed in another universe), Energy Projection, Teleportation, Weather Manipulation, Can grant powers to others, Regeneration (High-Low), Reality Warping (His heart can reshape the entire universe), Resurrection (Can bring back the dead), Magic, Enhanced Senses
Attack Potency: At least Universe level (His mere heart has enough power to reshape the entire universe)
Lifting Strength: At least Class M (Much stronger than Ultimate Way Big)
Striking Strength: Class XMJ (Much stronger than Ultimate Way Big)
Standard Equipment: None
Intelligence: High (Is thousands of years old, Has conquered over 100 universes, Fought Sir George, Has knowledge on Magic)
Weaknesses: Diagon's mind control can be blocked by protecting the head with certain metals, as well as mana. As powerful as he is, Diagon is still bound to the rules of magic. Ascalon.