I've pugged Vet HelRa many times, and almost none ever beat the flame Spinner boss. I'm getting better though with new guild and I've learned a few things that could help other pugs n noobs like me.
First is label the splits 1,2,3,4 and everyone needs to know their position. Combat text will reveal the real one that doesn't have all the crazy numbers when you hit it. Somebody needs to call out which one is the real one to direct the DPS.
Venom Arrow, Crushing Shock or some other ranged interrupt will be majorly helpful here. Healer should stand back a bit and get those interrupt when they start to spin anyone close should try to get the interrupt as well. Don't let them keep Burning you up.
I'm a bit hard headed so it took some time to sink in, but you can't dodge roll out of the AOE that comes from the spinners feet. But you can block and be just fine. That's right. Just stop your rotation and hold block as soon you see big red circle growing under the Spinner.it only last a second, and sometimes it's really fast and you don't see it in time, but just block.
There's a meteor that comes down and stuns someone. It often aims the healer in the middle somewhere. After you get up from the stun, walk away from the ground AOE it leaves behind. If it's right in front of Spinner move around it and continue beating on her.
If someone goes down, get them up. Fast. If your picking up and you see the Spinner AOE thing, stop and block. If you get meteor while picking up, move. Keep up with the interrupt.
We've had 4 people go down and still get it done with timing the pickups right and getting them when it's safe.
It's also great for the healer to have Barrier. It will save you way more than warhorn or healing Ultimates.
There are some other ways to do it, but I'm not real familiar with. Somehow you can run to the other room and hide (line of sight) around the corner and ultimate dump the boss. That's supposed to burn her down real fast, but I don't know all the inns and outs to it.