History
The Infinity Crusher was a special item forged to destroy the Infinity Stones. After killing her father Thanos, Gamora used the Crusher to dispose of the stones while Eitri melted his Infinity Gauntlet.
Sometime later, the Watcher recruited Gamora into the Guardians of the Multiverse to deal with the threat of Ultron. She revealed to them that they were going to destroy his Infinity Stones using her Infinity Crusher. The Guardians were successfully able to subdue Ultron and Gamora activated the device on his armor; however, it failed to destroy the stones. Ultron then stated that it didn't work because the Infinity Crusher was only capable of destroying the stones of her reality because they are slightly different in every universe.[1]