Doctor Strange: The Oath is one of the more celebrated recent runs on the character by Brian K. Vaughn and Marcos Martin. It took the origin story and expanded on it, creating the character of Nicodemus West who would continue on into the Doctor Strange film as played by Michael Stuhlbarg. It's also the trade that actor Benedict Cumberbatch posed with while visiting a local comic shop while in full costume and filming.
Now, TL; DR (Too Long; Didn't Read) is breaking down the series into just over 3 minutes of animated fun. This episode was written by Max Dweck and Noah Sterling and drawn by Jina Noh.