Prior to his car accident, Stephen was extremely egotistical, arrogant, stubborn, and narrow-minded; however, this changed after the accident, which left Stephen a broken man, albeit also one extremely determined to heal himself.
After discovering the existence of the supernatural and becoming more involved in the dimensional wars; Stephen becomes far more selfless, moral, honorable, honest, responsible, open-minded and protective of his friends and comrades alike, he is also not about apologizing or admitting when he is wrong, as he apologize to Christine Palmer, his ex-girlfriend and love interest, for his arrogance and for taking his frustration out on her when he temporarily lost the use of his hands.
Stephen is highly intelligent, as he came up with several creative ideas; despite the fact that he has only recently become a sorcerer and had no experience compared to Mordo and his enemies.
Powers and Abilities
Magic: As a sorcerer, Steve is extremely powerful, after months of study and practice under the tutelage of the Ancient One, Steve excels; becoming an exceptionally powerful sorcerer.
Eldritch Magic Manipulation: Steve is able to create, shape, and manipulate Eldritch Magic.
Teleportation: By using a Sling Ring, Steve is able to open a fiery portal to another location; gaining ability to across both the physical world and the dimensional Multiverse.
Interdimensional Travel: By using a Sling Ring, Steve can travel between different dimensions and universes, crossing over different planes of existence or traveling across various forms of reality.
Astral Projection: Steve is capable of separating his astral spirit from his body, gaining access to the Astral Dimension; he can also make his spirit from visible to other individual(s), if he chooses to.
Chronokinesis: By using the Eye of Agamotto, Steve is able to control the flow of time, be it on a small or massive scale, notably to turn back something to a previous state, to accelerate its time in order to apply changes that have not happened yet, or to lock it in a time loop, resetting its state until he stops its effect.
Master Physician: Steve is one of the world's best neurosurgeons. His skill allowed him to perform nearly any form of operation with little to no mechanical assistance flawlessly. His skills are so impressive, that Steve was targeted by HYDRA's Project Insight as a potential threat long before he ever became a sorcerer.
Multilingual: Steve is capable of fluently speaking English and Sanskrit among other languages.
Eidetic Memory: Steve has a perfect photographic memory and his perfect recall had originally greatly aided him in medical school, helping him earn his MD and PhD simultaneously; he even managed to Steve managed to master entering the Astral Dimension, and was able to understand how to use the Eye of Agamotto after reading a portion of the Book of Cagliostro's instructions only once.
Hand-To-Hand Combatant/Martial Artist: Steve has some skills in hand-to-hand combat and martial arts.
Weapons and Equipment
Sling Ring: A Sling Ring allows Steve to open a fiery portal to another location; regardless if it is to another location on his Earth or another dimensional Multiverse.
Eye of Agamotto: The Eye of Agamotto allows Steve to Manipulate time itself, creating an endless loop, until he stops its effect; its other powers are currently unknown, as its powers comes from an Infinity Stone.
Cloak of Levitation: The Cloak of Levitation allows Steve to levitate and hover in the air.
Former Weapons and Equipment
Quarterstaff: Steve used a Quarterstaff during his training at Kamar-Taj.
When New York went under a powerful sleeping spell cast by Nightmare, Doctor Strange enlisted the help of Danny Rand, also known as Iron Fist. He questioned Iron Fist's choice in bringing Spider-Man with him. Doctor Strange explained to them that it was the work of Nightmare and claimed that faith had brought Spider-Man to be with them. Strange brought Spider-Man and Iron Fist to the Dream World to stop Nightmare. Doctor Strange fought against Nightmare, his horse Dreamstalker and his army of Dreamons, who overpowered him. For a while, Strange believed that he was too weak against Nightmare and lost his magical powers. He was convinced by Spider-Man that it was just a dream and regained his powers, and with the help of Spider-Man and Iron Fist, they sealed Nightmare in a magic box.
After they defeated him, Doctor Strange thanked Iron Fist and Spider-Man and reminded them to go back to Midtown High school before anyone figured out where they had gone.
In addition, Doctor Strange appeared in the 2016 Super Heroes Half-Marathon RunDisney event at Disneyland and hosting the Doctor Strange 10K run. It's currently unknown if Doctor Strange will continue to appear annually like other Marvel characters that appear in the event every year.