Guild Wars 2 – Magic Users

From the Black Citadel travel to either the Vault Waypoint (just prepare to fight your way out) or head to the Temperus Point Waypoint and head to the marker which is nearby. At the marker you will enter the instance to begin the quest.

Once inside the instance your friend will approach you and tell you that the area is covered in Flame Legion. Start off to the South and head to the Southern face of the plateau below Exterminatus HQ. As you head there you will need to fight through some Flame Legion. One option you have is look in the surrounding area. There you will find boulders that you can pick up and throw at the Flame Legionnaires that are between you and Soure Doomsday. Around the first bend you will encounter the very first of them. This is a group of 3 Flame Legion with a Lashtail Devourer as well.

Turn to the South after that and hug the rock wall. You will need to fight through another trio of Flame Legion. This group has a Blademaster, Shadowblade and a Stalker. Hugging the wall will put you into conflict with a Lashtail and a duo from the Flame Legion. Just keep along the wall. With proper timing you can make past the Exterminatus without much more conflict. There is only another pair of Flame Legion Stalkers immediately. There is a Bladestorm and Blademaster that patrols around there as well, fair warning.

When you reach the plateau there is another trio of Flame Legion that you need to quickly kill: a Blademaster, Stalker and Shadowblade. Just head around the plateau from there to reach Soure Doomsday:
Hero: “Soure Doomsday? Rytlock Brimstone sent me. My Warband needs you.
Soure Doomsday: “Needs me? Tell that to my old Warband. I was raised with them. Fought beside them. Yet they still didn't trust me. All I did was meet with a Flame Shaman, and they called me a traior. Thing is, I was there to assassinate him and steal his magic. I'd never turn my back on the Blood Legion.”
Hero: “That's why I'm here. I need someone with your talents to help rebuild my warband. Join us.”
Soure: “The Flame Legion already made me an offer: join or die. As a gladium, I didn't have much choice. Get me out of this shotgun wedding, and I'm all yours.”

Turn to the Southeast now. It is time to face down the Flame Legion and get Doure Doomsday out of the deal he was forced to make. Start over there. You have a turret and 2 of the Flame Legion. This is quickly brought up to the a full on major brawl with at least 4 -6 more of the Flame Legion coming at you

After all of them fall it comes down to Flame Recruiter Szagur:
Flame Recruiter Szagur: “We had a deal. Without a Warband to back you up, you're dead meat.”
Hero: “I made Soure a better offer. Stand aside, or –“
Szagur: “Or what? Save your empty threats. It's too bad, really. You could've had more power than in your wildest dreams, Soure.”
Soure: “My dreams involve a barrel of whiskey, an Ash Legion Minx, and you, dead at my feet. Time to make that last one a reality

He fights with 2 Embers as back up. They will likely fall to area attacks or your support in the form of  your friend and Soure Doomsday. Just pound away on this Flame Legion Shaman. He will call in 3 more Embers when he gets down to half health. Take them out and take care of him as well. Once it is all said and done you will have another conversation with Soure Doomsday:
Soure: “You saved my tail.”
Hero: “If I had any doubts about offering you a spot, you just crushed them flat. We could use ten of you.”
Soure: “You don't need ten. Just me, and that barrel of whiskey.”
Hero: “That can be arranged.”

With that, you will complete this quest and it is time to begin “Rage Suppression.”