A spirit will spawn floating on top of the platform shooting a light to the Aspect making it visible and vulnerable but only to the player who was attacked by the Beam
This is the part that kept messing with our group. I honestly thought it was bugged as I saw and CC'd it the first attempt but then never saw it again.
Joined some pug. Our run was pure chaos and we had no idea WTF was going on during the boss. Wiped once, killed him the second try. Rezz orbs have been popped.
Did a bunch of runs on T1 afterwards for achievements and mechanics and kind of got a hang of it. The need of additional players to unlock the next part of the fracal was a cunt move by Anet. Heaven forbid people solo something.
Edit, after a few days of experience:
Yeah I was extremely lucky to get a group that killed the boss on the first try. Couldn't repeat a T4 kill ever since. People fail add management and AoE phases and the CC cockup cascade is an ever-looming threat.
In general another raid training tier encounter for the cHalLengIng ConTenT crowd.