For Voss gear does help, but not panicking with all the crap going on was the bigger hurdle, heh.

For my team P1 is tank and spank. When she goes back to the center and starts to levitate, that's when I blow cooldowns and DPS her as much as possible until she's immune. You don't want to do it any earlier because you'll be wasting time if she Dark Blazes you. With my current gear, she doesn't even get to do the Dark Blaze, but when she does, everyone goes on follow, run through her and along the wall {Glyphed Riptides from the Resto Shaman to top off if anyone strays through the fire}.

Phase 2, everyone DPSes until she starts to cast Fixate. DeadlyBoss Mods alerts to whom she's casting it on and because of the cast time I get fair warning so I can gather everyone up. If she fixates on DPS, everyone goes on follow and I kite her until I get a good lead, turn, cast from range, kite again. If she fixates on my healer or tank, the healer stays on follow and I IWT my DPS so they can tear her up while she follows my tank/healer. If I've timed it right, my cooldowns should still be running for a bit to help burn out Phase 2 a bit.

Phase 3, with any luck my P1 burst should have gotten her really low. She'll Dark Blaze at the start, just have them all follow along the wall like before until they stop streaming fire, then use the same process as P2 on her.