Red Death is a two-shot crit hit kill in the Crucible if you land 2 clean bursts, and Bad Juju will take more. Three Little Words from the Crucible vendor has the same impact as Red Death and is also a 2 shot kill, and the sights on it are pretty good too (and you get Third Eye). The health regen on Red Death can come in handy once in a while in PvP firefights when engaging multiple enemies, although its best use is in the Crota hard mode fight where there is no health regen.