In 2017, Doctor Strange took possession of the Stone and used it to defeat Dormammu. The following year, during the Infinity War, Doctor Strange relinquished the Stone to Thanos in exchange for sparing Iron Man's life.
Strange went through over 14 million scenarios and found only one that would work and in that one, Tony lived. What Strange did by giving the Time Stone to Thanos wasn't so much a trick as a sacrifice. Thanos rightly saw it as such, but more than likely assumed it was just a sacrifice for Tony's life.
What if Strange used the Time Stone against Thanos?
It's so simple, if Dr Strange uses the time stone means he will be in control over time therefore the Avengers would have won the battle and Thanos could lose either way.
Time Stone: As guardian of the Eye of Agamotto, the Ancient One protected the Time Stone which was inside. She gave it to Hulk so that he could resurrect the victims of Thanos' Snap in his universe, and it was then returned to her by Steve Rogers.
Why Doctor Strange Gives Thanos The Time Stone Explained
Is the Ancient One stronger than Thanos?
STRONGER: THE ANCIENT ONE
She was the true Master of the Mystic Arts and her skills in sorcery would have easily matched Thanos. This is a battle that might have even succeeded with Thanos carrying the Infinity Gauntlet.
The Ancient One refused to give up the Time Stone for the Hulk, citing that she could not alter his timeline and leave hers undefended, despite Hulk promising that he would return the stone to her at the exact moment it was taken.
Then, we have the Time Stone, represented by, you guessed it, the newly all-powerful, time-traveling Loki who now sits at a throne at the center of the multiverse holding all timelines together with his very green magic.
It's been noted that Thanos was more of a cosmic threat than a mystical one. Since Strange, as a Master of the Mystic Arts, deals more with the mystical side of things, this might give him an excuse as to why he never caught on to the Mad Titan until it was far too late.
Summary. The Doctor Strange variant with the third eye likely got it from using the Darkhold, hinting at a possible evil future. Doctor Strange's third eye is rooted in Marvel Comics mythology and represents a higher level of consciousness and mystical power.
Why didn't Dr. Strange use Time Stone to save Tony?
Reversing time to undo Tony's death would also undo the outcome of the event that led to his death—his Snap. In order to save Tony, you have to rewind to before he snapped, which puts Thanos and his whole army back, which ultimately solves nothing.
Although Strange is believed to be innately more powerful than his predecessor, he was far less experienced by the time that Thanos arrived on Earth, giving the Titan an extra edge over his enemy.
Against Dormammu, Thanos without the Infinity Stones is already dead; it's only a matter of time. But Thanos with the stones? It all depends on where the battle is fought. In the Dark Dimension, Dormammu can win nearly any fight.
In order to save Tony Stark's life, Strange gives Thanos the Time Stone, which effectively makes his victory an inevitability. As the Sorcerer Supreme fades into dust, he tells Tony that there was "no other way" despite the fact he foresaw 14,000,605 other potential futures.
Why did Dr. Strange hold up one finger in Endgame?
In Endgame, Strange locked eyes with Tony during the final battle and raised his finger: This is that one chance in over 14 million. Tony understood immediately. It would require sacrifice. A life.
Why didn t Dr. Strange use the memory spell on Thanos?
So for whatever reason, the memory spell simply wasn't part of that chance. Other commenters also offer some valid reasonings, such as the spell requiring the "willing participation of the subject," as well as the fact that Thanos already held some stones, which might've allowed him to negate the spell.
Being trapped for millennia would certainly have an impact, but as presented, Thanos is a true unstoppable force. And a time loop isn't quite an immovable object. The other key difference between the two situations is knowledge of the Time Stone.
What did Loki realize when he saw the Infinity Stones?
Secretly, he has to know that the Stone had bested him. He, Loki, God of Mischief, brilliant trickster, hadn't been strong or clever enough to not be affected by the Infinity Stones. But the TVA is, making it impossible for Loki to avoid the truth that the TVA is more powerful than him.
And though you might expect 2023 Nebula to start bleeding out or disappear, she's completely fine. That's because when 2014 Nebula traveled to the future on Thanos' orders, she created a split timeline.
Exactly why a scene featuring the Avengers kneeling before Tony Stark was cut from the film's final version. Revealing all in the AMA session, Joe and Anthony told fans that they wanted to avoid a "fight" between the kneeling scene – which we've explained here – and a later moment from Tony's funeral.
We assumed that she probably disappeared back to space. After all, 2014 Gamora was technically still part of Thanos' army. She probably had some things to sort out having betrayed her adoptive father and witnessed his death at the hands of the Avengers.
