Roughly 10 pulls on this boss and handling the CC's, Battle-Mender Interrupts, etc... of phase I appears to be straightforward. However, we're having trouble healing through the "Rain of Blades" in Phase II. I immediately noticed that the DBM timer was completely off for this ability and did some digging.
As mentioned in the latest track changes of DBM found here, the boss seems to cast this ability every 45-60ish seconds. Our logs confirm the variation, although ~80% of the casts happen every 1minute with the odd 45 second ICD.
I was planning on building my own set of Weak Auras with ICD timers of 45 and 60 seconds, attempting to cover every 60 second "Rain of Blades with AA/Spirit Shell and other healing CDs for those nasty 45sec ones.
Anyone out there have some nice tricks for dealing with P2 Rain of Blades timing/healing?