WARNING: The following contains major spoilers for Defenders #1, available now from Marvel Comics.
Of all the heroes in the Marvel Universe, few know what waits in the shadows better than Doctor Strange, although that doesn't mean he can't still be caught off guard from time to time. This proves to be the case when a mysterious visitor teleports into his Sanctum Sanctorum in Defenders #1 by Al Ewing, Javier Rodriguez, Alvaro Lopez, and VC's Joe Caramagna. Luckily this mystery man hasn't come to start trouble, but rather to ask for Strange's help in dealing with a new threat to reality.
Although the Masked Raider is kind enough to introduce himself upon entering the Sanctum Sanctorum, that doesn't keep the Sorcerer Supreme from going on the offensive. After launching what should have been a vicious assault, Strange notices that his uninvited guest is somehow immune to the effects of his magic regardless of his apparent lack of training in the mystic arts. The Eternity Mask that the Raider wears is surely part of the reason for his resistance, and even though the good doctor is familiar with the mask, he has no idea who now wears it.
The Eternity Mask is cut from the cloth of the celestial being Eternity and has played an important role in human history since the days of Camelot. Granting its wearer both cosmic awareness and power equal to any who oppose them, the mask fell in and out of various hands over the years before finding a more permanent home with cattle rancher Jim Gardley. For over thirty years in the 1800s, Gardley fought against injustice as the Masked Raider until his life was unceremoniously ended.
Eventually, the nefarious group of scientists known as the Enclave would come to possess the Eternity Mask, and it was with one of their own that the current Masked Raider would discover his true calling. Scientist Jerome Hamilton had used the Eternity Mask to become Blind Justice, and as such he waged war on the Enclave for their crimes. When Hamilton was killed by his former associates, he passed the mask off to its current owner who was first introduced in 2019's Marvel Comics #1000.
Now it seems that the Masked Raider is back in action. Coming to Doctor Strange wasn't just a good idea, it was likely the best he could have had, but it still hasn't gone the way either of them expected. Much like with his original Secret Defenders, Doctor Strange has turned to the power of the tarot to uncover which allies he would do best to call upon for the upcoming battle.
Even if neither of them were expecting the likes of the Silver Surfer or Red Harpy to appear, the fact that the cards confirmed the Masked Raider's place on the team is an indication that he is as benevolent as he claims to be, even if his true identity remains a mystery.