Holy cow, we have to pay attention to trash again!
Ruby Sanctum, the new one-boss raid instance for Wrath, is a fun and challenging fight. And, it actually has trash to which you have to pay attention!
Halion is a 3 phase fight. The first phase has the raid in the normal realm, and requires a straight forward "move out of the group" debuff that can cause serious chaos if the affected player isn't paying attention. Once the group gets Halion down to 70%, it's off to the Twilight Realm!
P2 is the most challenging component of the fight. The entire raid enters a twilight portal, and proceeds to focus fire on Halion. There's still the move or blow up the raid debuff, but complicating matters now is the Twilight Cutter mechanic. This is effectively a death ray that is active between two points which bisect the room. The tank must constantly rotate Halion in order to keep the rest of the raid out of this cutter (well, the raid has to pay attention, as it's not the tank's responsibility to keep you alive). Once the raid gets Halion down to 50%, the encounter transitions to P3.
P3 is the last phase of the fight, and is essentially P1 and P2 combined. The raid splits into two groups, divided between the two realms. The final complicating factor here is the need to dps both aspects down equally; if dps is out of balance, one aspect gains power and quickly wipes the raid.
While we were disappointed there was only one boss in Ruby Sanctum, the Halion fight goes a long way to easing that disappointment. Good job folks!