WARNING: The following contains spoilers for The Flash #764 by Kevin Shinick, Will Conrad, Hi-Fi, and Steve Wands, on sale now.
The Flash #764 sees the return of one of Barry Allen's long-time villains, Dr. Alchemy, who now seems deadlier than he ever was before. This time around, the possessor of the Philosopher's Stone seems to have a personal vendetta against the Scarlet Speedster and wants to embarrass The Flash as much as he wants to defeat him.
Dr. Alchemy, or Albert Desmond, breaks out of Iron Heights Penitentiary by turning the prison's walls into molten lava and raindrops into bullets. With all the other prisoners, bystanders and police in danger, The Flash rushes to the prison to stop his old nemesis. Barry notes that "the challenge is always separating him from the [Philosopher's] Stone, which won't be easy this time." The Stone is what gives Dr. Alchemy his powers to transform the molecular structure of anything in the world, including the molecules of the human body, into any substance, and it appears that he has fashioned the Stone into a ring.
Barry tries to stay out of Desmond's sight for as long as he can while saving the police officers, but Dr. Alchemy notices the raindrops he turned into bullets are suddenly changing direction, indicating the direction in which he's running. Desmond shoots a beam and hits Barry in the face with mercury, which melts away Barry's mask and disfigures his face. The Flash's quick healing factor helps him recover, but Dr. Alchemy then turns the street into water. The Flash then focuses on saving all the police officers who are drowning due to wearing heavy bulletproof vests and equipment.
Desmond gets away and Barry uses this time to learn more about the Philosopher's Stone and its history. Barry senses that something is different about Dr. Alchemy and that he seems more powerful and deadlier than he has in the past. The Flash and Dr. Alchemy have been butting heads since Alchemy's debut in 1958's Showcase #13 as Mr. Element. Desmond has an encyclopedic knowledge of various forms of chemistry and has been on the hunt for The Flash for several years, even becoming part of Barry Allen's supervillain group, The Rogues.
From studying the Stone's past, Barry realizes that Demond isn't just using the Stone to grant himself immortality, vast knowledge and immense power, but that he is attempting "something nearly impossible... He wants to absorb the power of the Stone so he doesn't need the relic itself." If he accomplishes this, Dr. Alchemy will become unstoppable and almost god-like in his abilities.
Barry tracks Desmond down to an exhibit where he's trying to steal a responsometer that could help him achieve his goal. When The Flash goes after him, Dr. Alchemy steals the speed force from Barry's body. Being in such a vulnerable state, Alchemy could have killed Barry with ease, but instead, he punches him in the stomach. Alchemy wants everyone at the exhibit to see that The Flash was powerless to catch him. Defeating The Flash isn't as important to Desmond as embarrassing him and ruining his reputation as the heroic Scarlet Speedster.
Dr. Alchemy has made his mission personal as he successfully stole both the responsometer and The Flash's speed and is one step closer to achieving god-like, absolute power.