Anti-Gamma Arrows
Arrows invented by Bruce Banner. They contain a serum which temporarily depowers Gamma Mutants, forcing them to return to their human form.
The arrows were created as a way of containing the Hulk, but have since been used on other mutates.
When they were first created, Bruce was unsure whether they would depower or kill him. When the Hammers of the Worthy began transforming super-powered individuals, Bruce gave the protoypes to Clint Barton, who was the only person he trusted to use them. When Savage Hulk became the Breaker of Worlds, Clint was forced to use the arrows, which worked as intended, depowering the Hulk long enough for the Hammer of Nul to be safely contained.
Since then, Bruce has interated on the design, making the arrows safer and more reliable, and also creating dark versions which are compatible with Natasha Romanoff's Widow's Bite. It has become standard Avengers operating procedure for Natasha or Clint to carry anti-gamma arrows on any Avengers mission for use on Hulk or other Gamma Mutates they might encounter.
Creator
Bruce Banner
Bruce Banner