During an experiment to retrieve Quantum Energy for a recovering Ghost, Ant-Man was exploring the Quantum Realm when the Decimation happened and vanished everyone operating the Quantum Tunnel in Luis' Van, leaving Lang trapped in the Quantum Realm.
Five years later, Scott Lang was freed from the Quantum Realm by a rat that happened to press a button on Luis' Van. Scott, however, had only spent five hours in the Quantum Realm due to time working differently there, and quickly realized that he had arrived five years in the future. With that, Scott came up with the idea of using the Quantum Realm to travel back to the past and prevent the Decimation from occurring, which the Avengers agreed to.
Once Tony Stark figured out how to safely travel the Quantum Realm to reach other time periods, he developed special suits designed for time traveling. Hawkeye volunteered to do a test run with the special suit; however, Scott warned that with Hank Pym gone, they only have a limited supply of Pym Particles to work with.
With the test successful, Stark developed more special suits for all the Avengers participating in the Time Heist based after Hank Pym's designs. The suits were designed to materialize around the wearer's outfit via nanotech technology. James Rhodes' suit was integrated into his War Machine suit. During the Time Heist, the Nebula of 2014 stole the present Nebula's suit to infiltrate the Avengers in 2023 and allow Thanos to travel to the future in order to stop them from undoing the Decimation and take the Infinity Stones they had gathered.
Following the Battle of Earth and Tony Stark's funeral, Steve Rogers used the special suit one last time to return all the objects that had been stolen during the Time Heist to their proper time periods in order to prevent alternate timelines from occurring.
- Size Manipulation: The suits have the size-shifting adaptability down to subatomic levels that are also present on Ant-Man Suit to explore the Quantum Realm while enduring its adverse effects.
- Time Travel: A wrist gadget nicknamed by Tony Stark as a 'spacetime GPS' allows for displacement through time and space, which in turns allow the user to determine what time period and location they'll reach after exiting the Quantum Realm. However, this is limited to the amount of reserve Pym Particles the wearer is carrying, as a return into the Quantum Realm is required to visit other time periods.
- Suit Materialization: After a time displacement, the suit appears to retreat into below the wearer's 'spacetime GPS' and can be materialized when time travel is required again.
Behind the Scenes
- The suit is entirely CGI; no practical suits were ever built.