Raid Mechanics
The circles on blue do massive Raid-wide damage, so you all need to stack in them when they’re up (or at least some of the group, might as well do everyone). To damage him you just need boon strips to get rid of his invulnerability buff. Green does seem to be normal damage, red is definitely condis, but I think maybe the red orbs can hurt him too? The group I was in didn’t really test that.
L.F.E.
This has some discussion:
https://www.reddit.com/r/Guildwars2/comments/3n9l98/bw3_raids_feeback_thread/