Loki is a member of the race of Frost Giants of Jotunheim, although not a giant in stature. He possesses physical attributes equal to a fit average member of the race of superbeings, the Asgardians, such as enhanced strength; stamina (his Frost Giant metabolism grants him superhuman levels of physical stamina in practically all activities); durability enough to harmlessly withstand high-caliber bullets; and immunity to all known diseases and toxins, as well as some resistance to magic.
Loki is of genius level intelligence and has extensive training in magic, and possesses the ability to manipulate magical forces for a variety of purposes: energy projection, creation of force fields, temporarily increasing his own physical strength, granting superhuman abilities to living beings or inanimate objects, flight, hypnosis, illusion casting, and inter-dimensional teleportation.
Loki's magical abilities have been described as equal to those of Karnilla, the most skilled sorceress of Asgard. His illusion casting can fool cities, and through extreme effort, he has been able to break free of technology in the possession of Apocalypse.
Apparently, Loki possesses some extrasensory abilities and is capable of astral projection and casting his thoughts across great distances—even across dimensional barriers, like that between Asgard and Earth—even if he is unable to move. He cannot read the minds of other beings, although he can influence their actions, and once briefly hypnotized Thor, as well as controlling a flock of birds. However he could not coerce Thor to give him Mjolnir. If someone has evil thoughts, Loki can influence their actions even if he is in Asgard and the subject is on Earth, and he can influence other events to a degree, such as driving a missile from its path, or redirecting a radio signal.
Loki is an adept shapeshifter and can change into animals (examples include transmogrification to a salmon, horse, etc.) or impersonate other people, such as Thor or Captain America. However, he does not necessarily gain the abilities of whatever he turns into, although minor natural abilities such as flight in bird form tend to work. Loki may even mimic the abilities of some supernatural beings if he turn into such creatures, such as gaining a hypnotic gaze while he turns into a dragon. He has also turned clouds into dragons, and animated trees to attack Thor.
At times Loki imbues himself with magical abilities that enable him to withstand injuries that would prove fatal to another Asgardian, such as being beheaded by Balder. He has likewise successfully protected himself against the Controller's control disk, the mental influence of the Voice, and the power-sapping abilities of Rogue.
Loki crafted a method of cheating death. He will be reincarnated upon any "death" of his body now that he has arranged with the incarnations of death that his name is erased from the books of Hel.
Aside from his mystical abilities, Loki possesses a brilliant intellect. However, his arrogance, his passionate hatred of Thor, and all-consuming lust for power greatly impeded his ability to bring his well-laid plans to fruition. He is an expert manipulator and schemer, is sometimes armed with a sword, a whip, or a three-pronged spear and has used magical items (such as the Norn Stones) to enhance his powers.