Okay, I made it up to Atheon in the raid but had to quit early this weekend. Want to get him over and done with before the weekly reset. Looking for people who want to help me on Xbone right now, or in the coming hours. Preferably a few people who know what they're doing, since it's my first time doing the Raid and the whole gates/relic thing confused the hell out of me.
I'm a level 28 Defender Titan. Add me: BlueNinja BE
I'm on PS4, so I can't help you do the actual raid, but let me explain the whole fight real quick.
First thing's first, you're going to enter the arena and have a lot of mobs, and a thing called a Gatekeeper. That's what you're going to kill. Positioning doesn't matter, we let people go ham here. Once you kill the Gatekeeper, in the back of the room there are two
Sync Plates like you saw getting inside the Vault. While you control one, you open up that side's portal. You want to split into 2 groups of 3 here, and have one group defending a Sync Plate (and thus a portal) and one group going into that portal. Once inside, they'll have to pick up the Relic (last seen in the Templar fight) and then kill another Gatekeeper, along with some adds (additional mobs, for short).
Once the Portal group exits the portal they need to call out that they have done this. The reason is because now you need two people to go into the OTHER portal and do the same thing. You want 2 going into the portal, and 4 staying outside. So, at this point, you're going to want 2 people defending the opposite sync plate, and 2 people killing mobs that swarm the Conflux (which you need to defend, ala the Templar fight). Once the portal group comes out, the fight against the actual boss begins.
Atheon will teleport the 3 furthest party members 25 seconds into the fight. So, you want 3 people staying in the back, and 3 defending sync plates. Now what you do varies based on where you are. The party members that get teleported will have to kill Oracles inside the portals (I highly recommend having your portal group be the same group that goes in the second phase of the fight, after you kill the gatekeeper). Your relic holder will want to hulk-smash adds with the relic, while the other 2 kill the oracles. Once all the oracles are dead, all 6 raid members will get a buff and the screen will read "guardians decide their own fate," or something. While this buff is active Atheon takes 5x damage.
So, for the portal group, Atheon is a fight of "shoot oracles, shoot the boss, shoot oracles, shoot the boss" or "smash stuff, smash stuff, smash stuff, smash stuff." For the group outside, they will fight terrorist Harpies that want to blow up your face. Shoot em, run away, whatever works. Just defend the Sync Plates. When your portal group comes out of the portal, everyone should jump to the little platform in between the portals and the relic holder should use their shield. Focus the boss until you get to about 5 seconds left on the buff, and then your sync plate defenders jump back to their respective sides, and your portal-goers jump to the back of the room.
There's a lot going on at any given point in time, but because the fight is effectively split into 2 groups of 3 most of the time, it's key to have adequate communication and ensure that everyone is on the same page and isn't trying to go ham. It's incredibly difficult to recover if 2 or 3 people die in a short period of time, and the more deaths, the harder the fight will become overall. Your group should anticipate wiping 3-4 times as you get the hang of moving through portals as fast as possible to maximize uptime on the 5x damage buff, but also remember that wipes happen, and that they aren't necessarily a bad thing. At no point should people sit there pointing fingers, but rather try and figure out why issues are, in fact, issues.