Three incredibly powerful magical artifacts created by the superhero Magister. Each of the three had the ability to drain the powers away from a super, and then grant them to someone else. When he vanished, Magister gave the three Banes to three people that he trusted. All three were ultimately used - the first early on, the second in a failed attempt to steal Judgement's powers, and the third in a successful attempt at the same.
When Psiborg attempted to take the powers inside a Bane for himself, it self-destructed, due to Magister having carefully sabotaged it in case of just such an event. It is unknown how this sabotage functioned, but it was specific enough not to trigger when Timebender's alternate reality self did the same thing.