[Borderlands 2] 2 Sirens against Hyperius in UVHM - Immolate + Norfleet kill.
Siren's skill Immolate gives a 50% bonus to incendiary damage during Fight For Your Life. So, once Hyperius has less than 15-20%, a Siren lets him stomp her and spams him with her incendiary Norfleet. Being revived and entering FFYL immediatly again makes it even easier.
In this fight, my partner and I planned to get downed at the same time next to Hyperius but when it happened my partner wasn't close to him. We still made it.