In most situations you will want this on your back bar (either morph, #nobodycares).
It’s used when things get hairy, for low dps groups, and high dmg output (like the Overcharger 2nd & 3rd wave for Troll boss in vSO, various trash in vSO, starfall in HRC, and in Zhajassa’s second shield phase). Why? It applies Major Maim, which reduces target dmg 30%, an especially nice margin during some clench moments. In addition, the “Prism” passive helps you generate ult faster each time you cast a Dawn’s Wrath ability.
Thank you to Harven for a wonderful little add-on that lets you see different morphs of a skill. Super handy!