Doctor Strange: 7 Tony Stark Cameos That Would Rule
3. Ties Into Infinity Stones
Since it's going to be exploring the more magical side of the Marvel Cinematic Universe, it is widely expected that Doctor Strange will introduce another of the Infinity Stones into the world.
Space, Mind, Power, and Reality Stones have already appeared, but it's likely we'll see all six of them before Infinity War, and Doctor Strange is a perfect opportunity to bring one in.
More specifically, it's likely to be the Time Stone. Strange will have an amulet known as the Eye of Agamotto, which has the power to manipulate probabilities, or "screw around with time." We've already seen the Eye, and it's glowing green centre just adds to the idea of this being the Time Stone.
While it's unlikely Strange will tap into its full abilities - either through caution, or lack of true understanding - if he does figure out that it's an Infinity Stone (which, again, seems very possible) then he may well call up Tony Stark for advice on what move to make next, since he's still heading up the Avengers, and they're the people you would probably go to if you discovered a powerful, otherworldly device, especially since one of their members has a similar stone in his head.