how did john constantine get his powers

Yes, he did. John Constantine made appearances in the Sandman comics.

The Flash got his powers through a freak accident involving chemicals and a lightning strike. It's a classic origin story in the comics.

Deadpool got his powers through a messed-up experiment. His body was subjected to a procedure that gave him superhuman abilities, but also left him scarred and crazy.

Kraven gained his powers through a combination of genetic enhancements and intense training in various combat and survival skills.

The Hulk got his powers through a gamma radiation accident. Bruce Banner was exposed to a huge dose of gamma rays, and that's what transformed him into the Hulk when he gets angry.

Morbius gained his powers through a failed experiment aimed at curing his rare blood disease. The process transformed him into a vampire-like being with enhanced strength and other abilities.

Deadpool got his powers through a rogue experiment. A weapon program tried to give him enhanced abilities, but it went awry, resulting in his unique powers and messed-up appearance.

Kraven got his powers through a combination of genetic enhancements and intense training in the wild. He developed enhanced strength, speed, and senses.

Mysterio acquires his powers through a combination of advanced technology and illusion-creating skills in the comics.

Deadpool got his powers because of a botched scientific experiment. This led to his superhuman healing factor and other strange abilities. It's a wild story in the comics!