What about a key type item? Its super would send out a bolt that does damage, but also can unlock certain doors. There are two things I would do with this: Unlock cells in the prison of elders, the enemies inside will then either help or hurt you in the final boss fight. You choose how many to unlock if you find them and they are randomized. Say 10 cells and on a particular run 4 start shooting and fighting you and 6 start fighting them for you while you focus on the boss, similarly you could open like 4 and they all want to kill your fireteam, it would add a bit of luck to the roll. The other function would be a maze type event, where the relic can open doors in the maze. These could open to groups of enemies or chests or a devil walker or something. It would be random sets of layouts. Source: Prison makes me think of keys lol