"Uh, hi."

"She thought I was Loki in disguise," Tony tells 2018 Nat. "Wouldn't give up the Stones without a fight. I figured this was the least messy way to persuade her."

"I am convinced that you are probably not Loki! Maybe less convinced that you're actually Tony Stark, and, uh, me. Uh, where the hell are we?"

"New Avengers facility. I converted an old Stark warehouse upstate—that's where we were holding you back in 2012. We're in the same place, just different time."

"Uh-huh. And the magic portals—"

"Long story. We met some people from a different planet—multiple different planets, actually—after Thanos did his thing. On one of them some people have magic powers. There's actually wizards from Earth, too, that I don't think you've met."

"Alright. Can I see some proof that this 'Thanos' actually, you know, exists?"

They take her to the conference room and show her news reports about the Snap.

She's not totally convinced that this isn't some kind of trick, but the costs of continuing skepticism now outweigh the risks of being fooled.

"Wow. I should be here helping you guys—we all should—New York is nothing compared to this."

"Well, if you want to prevent it in your own timeline, I suggest destroying the Infinity Stones as quickly as possible. They do way more harm than good, as far as I'm concerned.

"If you want to stay, I'm not stopping you. But I need that suit back."

Past Nat takes off the suit.

Tony takes it, walks back to the spot where he landed, and time-travels back to five seconds after he left.

Meanwhile, Strange and Leareth step through the portal and emerge outside 177A Bleecker Street.

Strange seeks out his old mentor and mentally taps her.

:Stephen. I wasn't expecting you for another five years.:

:I'm from the future. After you, ah, die. Thanos murdered half the universe and we're trying to fix it.:

:That does sound like something that ought to be fixed! I'm on the roof. Come up and we'll talk about it.:

She modifies the Sanctum's shields to let him in.

Strange opens a portal to the roof and he and Leareth step through it.

There are several—mages?—on the roof, most of them flinging combat spells at the invading aliens. Among them, seemingly unperturbed by the chaos, is a bald woman in yellow robes. She has an Infinity Stone inside the disk-shaped artifact that she's wearing on a chain around her neck.

She looks curiously at Leareth. :Oh, you didn't tell me you were bringing company,: she tells Strange.

Then, to Leareth directly—:You are a magic-user, but not one I know. Where did you study the Mystic Arts?:

In Urtho's Tower, Leareth thinks. A long, long time ago. 

Saying that won't be at all informative for this mage from another world, of course. 

:I come from a different planet. A world we call Velgarth. We have our own schools of mage-training. ...I am very curious about your world's use of magic, you do not seem to have Gifts in the way we understand them: 

:I am curious as well, as to what you mean by 'Gifts'—my magic is something that, in theory, anyone can learn, although in practice few possess the mental talents to harness it effectively. And, if the connotations I'm getting from you are right, our magic isn't innate as yours is—we only harness it, mostly via artifacts made long ago by others greater and wiser than we.

:But this is a long story, for another time, I think. I would like to hear about how half the universe was murdered, and what you plan to do about it.:

:Thanos. You've heard of him, right? Thinks overpopulation is going to destroy the universe, so he decided to kill half of everything in it. Got all six Infinity Stones, did it with the snap of his fingers. I used that:—he gestures to the Eye of Agamotto around her neck—:to look into the future, try to find a timeline where we won. Turns out our only chance was letting him do it, then going back in time to borrow Stones from the past to try to fix it.: (He doesn't mention that they're not, in fact, on the one successful timeline that he saw.)

:I'm not sure that's a good idea.:

:Why not?:

:The Stones are—anchors of the universe. Removing one from a timeline, or having two copies of the same one, could have disastrous effects. If you try to fight Thanos with your copies, Stones against Stones, that will certainly be even worse. There's a possibility the universe would be destroyed. You almost certainly would be.: