[SPOILERS for Doctor Strange #382 ahead.]
Sentry, an immensely powerful character who has been both a hero and a villain in the Marvel Universe, has returned after three-year absence in the pages of Doctor Strange #382. Sentry was resurrected by the Apocalypse Twins in Uncanny Avengers, but fled into deep space in 2014. The character hasn't been seen since—until now.
Created in 2000, Sentry served as a member of Captain America's New Avengers, following the tragic events of "Avengers Disassembled". Claiming to possess the power of a million exploding suns, Sentry was one of the Marvel Universe's strongest characters. Unfortunately, his reputation as a superhero was tarnished not only by his evil half, the Void, but also by his association with Norman Osborn. During Siege, Sentry murdered Loki at the behest of Osborn and was launched into the sun by Thor. This appeared to be the end of Sentry, until the Apocalypse Twins restored him to life. Appearing to have turned over a new leaf, Sentry left Earth to become the cosmic protector of humanity.
In the beginning of Doctor Strange #382, we see the Master of the Mystic Arts ascending a mountain in order to procure help from a mysterious person, who Strange fears will beat him to death just for contacting him. Strange cryptically mentions that this man technically doesn't exist. We learn at the end of the issue that the person in question is Robert Reynolds, better known to the superhero community as Sentry.
Apparently, Strange "fixed" Reynolds, thus erasing the threat of the Void. But Reynolds, still afraid of the harm he could cause, has vowed to remain on the mountain in an imaginary house constructed by Strange's magic. Convinced that the universe is hanging in the balance, Strange tells Reynolds that he needs his help. Sentry is shown in the final panel before the issue ends. We're left with a teaser of "The Sentry vs. Asgard" for Doctor Strange #383.
It's currently unclear exactly what Doctor Strange and Sentry will be up against now that Loki is the new Sorcerer Supreme. However, we do know from the issue that Loki is searching for a spell called the "Exile of Singhsoon," which Strange refers to as the "nuclear codes of the magical world." If the spell is cast, it could give Loki access to all magic in the universe, making it imperative that Strange and Sentry find a way to stop him.
Doctor Strange #382 is available now. The story continues in Doctor Strange #383, which goes on sale December 20.