I run Fireborn for my sunsinger just for Nightfalls/Weeklies, because I have wiped a nightfall at the very end, with a sliver of health, because one of us did something stupid. However, as a Warlock, running defensive and emergency response, if my teammates are smart enough to collect orbs (you think this wouldn't be an issue), I will use my super to generate as many orbs as possible, and rely on them to use their supers to return the favor and keep my ass alive. It keeps a steady stream of damage, and an emergency protocol when needed.