The Reversal of the Decimation was the occurrence in which Bruce Banner wore Tony Stark's Iron Gauntlet. As Hulk snapped his fingers, the effects of Thanos' Decimation on the universe was reversed, with half of its population being resurrected.
As all of the Infinity Stones are gathered back into the present, the Avengers realized Black Widow sacrifice to gain the Soul Stone. Determined to not let Natasha’s sacrifice be in vain Tony Stark, Rocket Raccoon, and Bruce Banner began working on a new Infinity Gauntlet.
After the creation of the Gauntlet was complete, Rocket asked who was going to be the one to reverse the Decimation.
At the moment when the Iron Gauntlet was set for completion, Thor volunteered himself to put it on, but the Avengers held him back, saying he was neither physically nor emotionally stable enough to do so.
Bruce Banner volunteered himself, reasoning that as the Stones and his body contained mostly gamma radiation, he was the most likely to survive the use of the Gauntlet. While Tony ordered F.R.I.D.A.Y. to initiate lock-down procedures across the facility in case the Gauntlet's energies proved to be too powerful to contain, an alternate Nebula began to sabotage the quantum device as Banner put on the Gauntlet.
The Avengers began worrying for him as Banner channelled the power of the Stones through his body, severely scorching his arm in the process. Thanos' mothership emerged and crashed through the roof of the facility, destroying the quantum device, just before Banner snapped his fingers, bringing everyone who Thanos decimated back.