Constantine's blood is demonically tainted, initially by a blood transfusion from the demon Nergal, and later by sex with a succubus. His blood has been shown to have healing properties. It has also acted as a defense mechanism when attacked by the King of the Vampires.
Bitter Taste Defence
Constantine is a magician but unlike most magicians, Constantine rarely uses magical spells, unless he really has to, especially in combat. Some examples of Constantine's magic:
Used a pendulum and map to find the location of a magical disturbance.
Summoned the demon Nergal to destroy a monster for him, which it did (although John lost control, due to his inexperience).
Black Magic Cursing
Placed a curse on his father that caused him to waste away, casting a curse on a host for vengeance, putting a curse to a gang that put them into catatonic insanity, or using a spell that traps someone between the gaps of time. Constantine's curses are strong enough to affect demons.
bound, immobilized, and sealed the demon goddess Kali, and destroyed a demon using a spell. During the Son of Man arc, Constantine summoned a demon, but he made it physical thus rendering it powerless and vulnerable, allowing Header to shoot it with a shotgun. John also uses the right kind of spell than can destroy gods (Hellblazer: The Trenchcoat Brigade) or seal them away.
Spirit ward creation
Placed a magical sigil on Ellie's soul that prevented the forces of Heaven and Hell from tracking her, as well as using sigils to hide himself from Satan. He also placed various sigils on an abandoned caravan that he housed himself in to hide himself from the demon Nergal. Constantine can also write sigils in his bodies that protects him from magical attacks and possessions, and to prevent any demons from physically touching him.
Protection magic that John uses for defense against both supernatural and physical attacks.
Being chased by Nergal, Constantine opens a path to Heaven. He leads Nergal to the borders of Heaven where the angels attacked Nergal and ripped him apart.
Raised a golem.
Erased a man's traumatic memories, or mind-controlled a whole penitentiary of inmates to madly riot and bring him a cigarette.
Raised a group of murder victims as ghosts to attack their murderer, and raised soulstorms to attack his enemies.
Made people think he's someone or something else
John Constantine is an excellent con artist and negotiator. These skills are often more useful than his magical ones. Constantine faces most of his challenges relying primarily on his cunning. Even with pressure, lack of time and preparation, Constantine can think of a strategy to defeat his enemies in a fight, letting him outwit both Heaven and Hell while striking fear into them. He's a master tactician and strategist and he can plan a strategy on the go. Although his IQ is never stated he is known to possess great intellect. Constantine has fought against many of the most powerful; gods and great intellectual minds alike. His achievements stand amongst gods.
Constantine's skills in unarmed combat varies depending on the writer. Some portrays him as a poor physical fighter, while others as a capable hand-to-hand combatant. However, he has occasionally won fights, either by using magical weapons (Hellblazer Vol 1 217 and Chas: The Knowledge), fighting dirty (Hellblazer Vol 1 42, Hellblazer Vol 1 57, and All His Engines), or by quick-thinking . During his fight against the god-demon Nergal , John ripped the spine off of his back with ease. Aside from conventional close-quarters combat, Constantine also uses stealth to take down foes, like using illusions and sigils to sneak up on opponents.
With the use of his magical knowledge, Constantine can resist many psychic attacks such as telepathy, soul and body possession, and powerful mind controls. Constantine can even use sigils to block off omniprescence (Rake at the Gates of Hell).
he has vast knowledge of the occult
an extensive list of contacts.
Constantine has also exhibited considerable mastery in "stage magic skills"