So we've been working on the Eredar Twins. Our best attempt was hitting the enrage with the 2nd twin around 35%. The fight is a lot like Naj'entus meets Solarian, where you have huge raid damage and the ability to one-shot 25 people if you're not paying attention. There's also some 2 sec mass stunning tossed in just so the healers don't get cocky.
For the most part it's conflag that's wiping the raid. People aren't running out in time and half the raid is getting insta-killed. It sounds simple but it's not. You only have the 3 sec conflag cast time to figure out who's targeted and have them get out. Unlike other "zomg, do this!" fights, by the time you hear your name on Vent, you should have already been running. So this isn't a situation where someone watching the cast bars can hold the raid's hand and walk them through what they need to do. People have to look out for themselves.
From a healer's standpoint, it's all about keeping the raid alive. I pretty much spam Light Rank 7 the entire time. Last night I was covering the 2 melee groups (along with 2 Shamans). There's a Burn-like Dot, Flame Sear, that 3 people get (although I saw up to 6) that's the biggest raid killer. It does 7.8k dmg per person over 6 seconds. Combine that with 3.5k dmg to half the raid every 30 sec and mass stuns, and you have a good time on your hands.
The fight is doable, though, proved by the fact that we reached the enrage timer. The plan is to keep running only Sunwell (provided we have the right group comp) next week in the hopes we'll down Felmyst again and work on the Twins some more. I'm thinking we're going to need gear before we have a chance at Mu'ru. And skills. Lots of skills.