Strange stated that he used the Eye of Agamotto to look into the future to see the possible outcomes where they come out on top. Out of 14,000,605 possible outcomes for Infinity War, only 1 outcome is where they come out victorious. With this, we can safely conclude that using a time loop on Thanos will not work.
In short, Strange is wise. i believe that in the future that he did use the time stone, thanos may have acquired it and used it for different means, and as you said, using the time stone too much can tear the fabric of reality.
Because at the point that Doctor Strange became aware of Thanos' existence, he already had the space stone.
The short answer is that he *could* have (Thanos proved that one stone can affect the weilder of another when he used the Time Stone on Vision), but Strange had already secreted away the Time Stone magically, to prevent Thanos from using his own immense power to take it from him.
Sling Ring travel must only be for "short" distances (if you want to call planet-wide "short"). We only ever see people use it this way so far, Strange doesn't seem to be able to port them back to Earth from the ship or to get support from other heroes from Earth.
“The Eye of Agamotto still has magical properties even without the Time Stone – as any fan true fan of Strange would know. So it still reveals to him things that are unseen.”
It represents the wisdom of the sorcerer Agamotto and his fellow Vishanti, allowing Strange to see his enemies' true intentions and break magical illusions. Doctor Strange's third eye is originally a sign of a higher level of consciousness, and it can only be used by those whose souls are devoid of corruption.
Why didn't they just use the stones to bring back Iron Man in Avengers: Endgame? Because he wasn't killed by dusting, so it was impossible to bring him back. Even if they went back in time to get a different Tony Stark, they would risk bringing Thanos back to the present too.
Ultron's inorganic, vibranium body seems to protect him from some of the damaging effects of the infinity gauntlet: With that being said its either out of the stones ability to kill all life in the entire multiverse or Ultron's body couldn't handle it or both.
Strange willingly gave the Time Stone to Thanos to save Tony Stark's life. He saw 40,000,605 possible futures and outcomes of the battle against Thanos. He knew that Tony must stay alive so they could come victorious ultimately and restore the universe as it was before Thanos's snap.
As for why he isn't in Multiverse of Madness, not all the Avengers are always present for calamity. Vision could be out in the world trying to fully regain who he once was, assuming he hasn't already. He could even be grappling with the multiversal chaos in his own way.
Because he has the Time Stone. Strange could do anything to the time with that stone.
Yes, the loss of any Infinity Stone would make any individual weaker than they were before, Dr Strange is no exception.
Thanos definitely had everything planned and made a smart decision when he destroyed the Stones, as he not only saved himself from the temptation of keep using the power of the Stones but also saved himself from a potential curse like that of Red Skull.
Doctor Strange To The Rescue
We first saw it in Doctor Strange when Stephen used the Stone to reverse the events and bring back Wong. Something similar was carried out by Thanos when he brought back Vision. Hence, there's no reason to believe Strange couldn't have brought back Tony and saved the day.
Tony Stark asked, “How many do we win?” Doctor Strange replied, “One.” The 'one chance' scene in Endgame is Strange reminding Tony of that single scenario, and Tony realising that the only way for them to win is if he sacrifices himself.
Imagine, Tony survived after End Game, he could have his own replicated Pym particles, had a time machine in his suit and even had access to each timeline in the multiverse. Dr. Strange believed if Tony Stark survived then sooner he will be the most powerful being in the universe.
Introduced in Avengers: Age of Ultron, the advanced AI decided his own course of action and formulated his judgment about the Avengers. He was particularly disgusted by Steve Rogers. As per the AI's understanding, Captain America was a warmonger and would refuse to survive in a peaceful environment.
The movie doesn't explain why the Avengers didn't show up for T'Challa's funeral, but it isn't hard to see why they weren't there. The biggest reason is that there really are no Avengers right now, at least not officially. More importantly, those who spent the most time with T'Challa are currently off the map.
At the end of the war, Tony Stark falls into a coma while fighting Captain Marvel, spurring Riri into continuing his legacy as a hero. With the help of an AI duplicate of Stark, Riri designs an improved suit of armor and takes on the name of Ironheart.
When Tony Stark snapped, he, ever the wise-cracker, replied to Thanos' "I am inevitable" line with his own mic-drop "And I am Iron Man".
Tony Stark's death in Avengers: Endgame has left the MCU with a major hole to fill. While characters like Doctor Strange and Spider-Man could become the new faces of the shared universe, it will be Riri Williams who will serve as Iron Man's more direct replacement.
Doctor Strange's third eye (the Eye of Agamotto) in the comics, according to Bustle, represents wisdom of the sorcerer Agamotto and his Vishanti. The Eye allows him to see the true intentions of his enemies and break down all magical illusions.
What is this? Yes, the Eye of Agamotto is one of three mystical Eyes created by Agamotto in the comics, accompanying the Eye of Power and the Eye of Prescience. First appearing in the Strange Tales series from the 1960s, the Eye has nothing to do with the Infinity Stone outside of the MCU.
The Eye of Agamotto appears in several forms of Marvel-related media, such as the Marvel Cinematic Universe, in which it contains the Time Stone, one of the fictional universe's Infinity Stones.