Warning! SPOILERS Below For Avengers: Infinity War!
What does the destruction of the Mind Stone in Avengers: Infinity War mean for Scarlet Witch? This may seem like an odd question considering that Wanda Maximoff is among the beings numbering half of all life in the universe killed by Thanos' finger snap. The Great Titan completed the Infinity Gauntlet when he used the Time Stone to reverse time after Wanda used her powers to destroy the Mind Stone. Thanos tore it out of Vision's forehead, killing the android - but what kind of effect could that have on her abilities?
Of all the shocking deaths at the end of Infinity War, Vision's was unique. He's the only Avenger that didn't die thanks to Thanos' finger snap, meaning any mechanism that reverses the deaths of half the Avengers (some of whom we already know are returning) might not impact Vision. Or, even if he is brought back to life, it could be without the Mind Stone.
Related: What Is Vision's Future In The MCU?
Regardless, despite fading into ashes while she mourned her deceased lover, Wanda's story is not over and neither is Vision's. Elizabeth Olsen and Paul Bettany are both confirmed to return for Avengers 4. Their relationship was one of the emotional centerpieces of Infinity War; in a welcome reversal of the 'damsel-in-distress' trope, Vision being injured by Corvus Glave in Scotland meant Wanda had to become her protector for the rest of the film. Aware that the Mind Stone could not be allowed to fall into Thanos' hands, Vision pleaded with Wanda to destroy it, she eventually gave in, holding off the Mad Titan in the process, but, unfortunately, Thanos outsmarted them both with time travel and won anyway.
If and when Wanda is resurrected, will she resume being the same powerful Scarlet Witch? The Mind Stone gave her psionic energy to manipulate objects and influence the minds of others. Her "neuro-electric interface" also lets her create illusions in people's minds, an ability she hasn't utilized since she used it on the Avengers in Age of Ultron. After becoming one of Earth's Mightiest Heroes, Wanda has relied more on her abilities to physically move objects.
However, Scarlet Witch ranks high as one of the most powerful Avengers. As one of the few characters empowered by an Infinity Stone, the upper limits of Wanda's abilities have not been explored. However, she was able to simultaneously hold off Thanos' advance while destroying the Mind Stone so that's an impressive barometer.
Related: What We Know About Avengers 4
Wanda isn't shown using her powers again after Thanos acquires the Mind Stone, but by then, Wanda was totally exhausted from the sheer effort it took to hold off the Titan and crush the Stone. Plus, she was distraught from witnessing Vision's death. It has never been suggested that Scarlet Witch's powers are dependent on the Mind Stone's continuous existence - her abilities seem innately her own regardless of the state of their original source.
The MCU's Scarlet Witch is a much more straightforward character than her comic book counterpart. 'Convoluted' is an accurate word to describe Marvel Comics' Scarlet Witch, whose history and powersets have been retconned several times. Essentially, the comics' Wanda is Magneto's mutant daughter and a practitioner of Chaos Magic, which allows her reality-altering abilities. She most infamously reinvented the Marvel Universe and then eradicated mutantkind in the House of M storyline. The Wanda Maximoff of the MCU has more simplified and elegant powers and, despite enduring trauma of her own, her mental health was comparatively stable before she died in Infinity War.
If Wanda is resurrected in Avengers 4, her proven ability to destroy an Infinity Stone could be a deciding factor against Thanos. The Mad Titan may have the Mind Stone, and that could influence Vision's ultimate fate, but there's nothing to suggest Scarlet Witch's ability to be a formidable opponent against Thanos will be impacted by the stones on his gauntlet.