Ironsides

Ironsides is a new vigor introduced in Bioshock Infinite: Burial at Sea Episode 2. It allows the player to capture bullets in mid-air and contain them for further ammo. It is first found on the First Lady Airship, when Elizabeth uses the tear to gain access to Columbia.

Strategy
As ammunition is limited in Burial at Sea: Episode 2, Ironsides is a good way to replenish ammunition. However, this strategy does not go well with  Ryan's Splicers, as they use no ammunition. Upgrades for this Vigor can be found around Rapture and Columbia.