Load up
ACT V - Pale Horse on
Insane difficulty in co-op.
I recommend a set-up where 1 person gets all the Longshot ammo, and the other gets all the Torque Bow ammo. The keys to success are speed, accuracy and perfect reloads! Enter cover as soon as you start the battle. The strategy is pretty straight foward, you'll need to generate "light" near general RAAM in order to get the Kryll off him, so that you can deal more damage to him. Do this using the Torque Bow explosions, or the grenades. As soon as the Kryll come off him, the sniper should lay as many headshots as possible into him getting perfect reloads, repeating the process as many times as possible as he comes towards you. Once he's close enough, toss all your grenades at his feet to do a large amount of damage. If you're fast enough, you should be able to defeat him before he reaches you, however if you are not, you will need to make a quick and difficult escape towards the other side of the ship and continue with this process. The reavers can be left alone for the most part but will damage you if you move from the initial location, so watch out for them if you need to extend your time in the boss battle. Eventually you should be able to kill him without being downed, and the achievement will unlock!