MCU: 10 Cosmic Villains For Phase 4
3. Magus
Magus is essentially an alternate version of Adam Warlock who was created to be a champion for life itself. He was taken from his reality by Lord Chaos and Master Order, who sought to bestow upon him all their teachings and secrets to help he be the champion of life they saw him becoming.
This went horribly wrong, however, as the process of being taken from his reality took him 5000 years back in time and the exposure to all the knowledge these cosmic beings were trying to implant in him drove him mad. He conquered the planet he was being kept on and founded the Universal Church of Truth.
Magus has an almost identical power set to Adam including cosmic energy manipulation, enhanced physical strength and cosmically bolstered endurance.
As we've yet to see Adam Warlock properly in the MCU, there may be a chance that Marvel want to explore his evil counterpart once he arrives. Something Adam does with the Gauntlet could trigger the creation of Magus, which has happened in the source material in the past, and his creation could be left for an after-credits scene to set up a whole new arc.