It basically turn you into a super saiyan for 15 seconds. Increases armor recovery, decreases damage taken etc for about 15 seconds. It also pretty much instantly recharges your grenades and melee ability so you can just spam them. I use it and I think it's way better than nova bomb, I literally tossed out 8 solar grenades in one go. You also generate an orb of light for every enemy you kill, so if you get a bunch of dregs you can really help boost your team's supers. Forgot to add this; it makes your grenades and melee MUCH more powerful. This is my radiance strategy; activate, scream like braveheart, rush in to all the things, grenade and melee spam, kill all the things.