Having trouble beating Atheon? Your problems are solved. My clan figured out a way to beat him in 4 portal runs (about 5-6 mins). He's really not that hard, and with practice, your team will be able to beat him in no time! So listen up!
You need all six people and at least one of them needs to be a Titan. That Titan is the key because he has a bubble shield the makes the guardians that goes into it have damage boost. VERY IMPORTANT!!! Another thing you need to know is which portal is on which side. From where you spawn, green is on the right and yellow is on the left. And lastly, your three best players need to be the group that gets teleported. The outside group has it pretty easy.
Now on to the strategy. When the portal group gets teleported, they need to call out if they're in the green room or yellow room so the outside group knows which portal to open up. After that the person with the highest health grabs the relic and heads down to kill the enemies in the room along with another portal group member. The other member of the portal group needs a good gun to focus on killing all seven oracles. By the time he's killing the fourth oracle, the other two should have the enemies dead. Everybody cleanse, kill the rest of the oracles, and cleanse one more time after exiting the portal.
Now the outside group. It's your job to clear enemies while opening the right portal for the portal group. That's basically it, but very important. And don't die!
Now when the portal group walks out of the portal, the relic guy should scream "middle now!". Five members (including the Titan) jump on the middle platform where no enemies can get you (the other member should be doing ad control). The relic guy has infinite shield with the relic then. Everyone can shoot out of it and Atheon can't shoot in. Note: from the time you kill the last oracle, you get a damage boost for 25 seconds. So everyone get to the middle quick! Now here's the great part! The relic guy stands towards the front of the middle ledge while the Titan drops his shield behind it. When a player walks in and out of the titans shield he gets a damage boost for about ten seconds. And yes, that does mean THE DAMAGE BOOST STACKS ON TOP OF THE OTHER DAMAGE BOOST!!!!! Get your boost from the Titan shield, step into the relic shield, and unleash hell on atheon! You'll notice a difference when you're doing thousands of damage each time.
When the timer in the left hand corner gets down to about 4 seconds, everyone scatter back to their positions. After that, it's like clockwork. Repeat this a few more times and you'll have Atheon beat in no time! It'll take a little practice for everyone to get their role down, but it works flawlessly.
http://www.youtube.com/watch?v=SRYzLiUzzxM