IMO
Its the Scion, Slate, Shadow nova one
This week I pugged him, and we got Scion, Slate, Time
Time is a joke, and basically is just there to be kept up to slow fireballs and is last
Scion literally makes this fight WAY harder on heals/tanks, and any combo with him makes it hard.
I would say that without the scion drake this fight is almsot 1 Tankable...
I also had to go with 3 healers with the above setup and they were failing...Not that they weere amazing but still...