It's supposed to be a support class, but doesn't do a very good job of it - coming from someone that has been a Sunsinger since unlock. Radiant Skin is completely worthless for support and Song of Flame only helps when the fireteam is in a compact space, but the grenade and melee boost doesn't actually help when Raids force the team together as guns do a much better job. This leaves Fireborn, which receives criticism to no end for being selfish when in reality, it's the best option. Solar Grenades are good for area denial but do little damage, Firebolt Grenades have no place in PvE whatsoever and Fuison Grenades are the exact opposite of Solar, doing lots of damage but to few enemies. Brimstone and Solar Wind are two of the most useless upgrades in the game across any subclass, and Flame Shield only benefits the user. Sunburst is a reasonably good support perk, but doesn't trigger reliably like Force Barrier does, neither does it even come close to making as many orbs. I don't see a reason why I need to justify the use of Gift of the Sun but from a support perspective, it doesn't do all that much to help unless your team has prolonged periods of inactivity for which a grenade with an effective 0 Discipline bonus can charge. Edit: Redeeming feature - Radiance is the Super that, with a bit of luck, can generate by far the most orbs in a single use Wearing Claws of Ahamkara with decent enough Strength, one Radiance can generate 14 Orbs (minimum, still not entirely sure on the Orb cap without extra perks, and I'm sure I've seen a few Fireborn uses drop an orb immediately)