Two episodes ago on "The Flash" season 3, we learned that Julian is Doctor Alchemy, and on episode 9, his identity was revealed not just to our heroes, but also to himself. It appears that when Julian becomes the Doctor Alchemy, his consciousness is blocked and a new being seems to control Julian. The Grim prophecy was also revealed on this episode.
Episode 9 opened with a flashback to Hindus Valley in India, where Julian, with some help, found the Doctor Alchemy's philosopher's stone. Savitar is the villain in episode 9 season 3 of "The Flash" and the whole team is trying to find out more about the monster, which can be unleashed through a philosopher's stone enclosed in a box.
The only information the team has about Savitar is that Julian has been curiously interested about it and in fact wrote a research paper for it. Barry went over to Julian to confront about the philosopher's stone and of course, the latter denied having knowledge of it, although Julian told Barry that Savitar is the original meta with speed.
As soon as Barry left, Julian heard a voice, egging him to wear the mask and become the Doctor Alchemy. Episode 9 of "The Flash" had a cameo role of Mark Hamill who played Earth 3's Trickster, who was subdued by Jay with the help of Barry. Upon returning to Barry's earth, Jay told him that Savitar became the "God of Motion" and if he were on this earth (Barry's), it must be because he wanted to duel with Barry as the latter is a threat.
Barry, on the other hand, spent some time with Iris. Iris convinced Barry that Julian and Doctor Alchemy might be connected. Cisco detected the philosopher's stone at the Central City building and both Jay and Barry went out to check it. Doctor Alchemy was using the building to revive meta's power from Flashpoint timeline. Savitar appeared just as soon as Barry and Jay did.
Barry handled Doctor Alchemy while Jay battled with Savitar. Doctor Alchemy was subdued and the philosopher's stone was placed in its box and Savitar disappeared. Barry took out the mask worn by Doctor Alchemy and discovered it was Julian after all. Julian was detained and will not believe "The Flash" that he is Doctor Alchemy. To convince him, he took off his mask.
Julian confessed he's been having some blackouts and the team planned on hacking into Savitar's mind. But when they did, the team learned about the grim prophecy: one shall betray Barry, one shall fall, one will suffer a fate far worse than death.
Scared of the grim prophecy, the team was intent on hiding the philosopher's stone somewhere impossible to be retrieved-the speed force. Jay and Barry may have succeeded on their plan but the philosopher's stone gave a blast which opened a portal into the future. Barry saw Iris destroyed by Savitar somewhere on Infantino Street.