Spoilers for Avengers: Infinity War ahead.
“There was no other way,” Doctor Strange wearily explained to Tony Stark just before disintegrating into ashes. Shortly before then, he had used the Time Stone to see over 14 million possible outcomes for their fight with that lying liar Thanos, learning they could win the fight in “only one” scenario. He then willingly gave the Eye of Agamotto (which holds the Time Stone) to Thanos to save Tony’s life. This has sparked plenty of fan theories already, including a convincing one about Captain Marvel and now a plausible theory that ties together multiple little details in Infinity War you may not have noticed.
When Thanos’ henchman Ebony Maw (the Voldemort-looking wizard) tries to snatch the Eye of Agamotto from Doctor Strange’s neck, it burns his hand:
Strange explains that he’s already cursed it. “Its a simple spell but quite unbreakable. […] You’ll find removing a dead man’s spell troublesome.” Since Ebony Maw can’t remove the spell, he begins torturing Strange to remove the curse, but he’s ejected into space before that can happen, which suggests — according to Redditor Mynccx — that there may still be a curse on the Time Stone, and no living henchman left to warn Thanos about it.
If there is a curse in place on the Time Stone, this would explain why Strange’s green spell runes show up when Thanos adds it to the Infinity Gauntlet:
The runes also appear when Thanos uses the Time Stone to undo the destruction of the Mind Stone:
If Strange placed a curse on the stone, that might explain why the Gauntlet was so damaged after “the snap”:
Mynccx theorizes that Strange’s curse might have been intended “to destroy the Gauntlet after its ‘snap’ or to interfere with the killing of half the universe, maybe by trapping them in the Soul Stone rather than them dying.”