For abyss, you know the drill. Hunter with max invis and agility. If possible, crouch to go invisible and if you can't, melee to go invisible. Learn the shortcuts to make everything go faster. Jump on the miracle rock at the end and snipe the ogres with black spindle/icebreaker. I will assume you know how to cheese the bridge. Max agility, max invis. Use bones of aeo to climb to the top of the tower, despawn enemies, glide across bridge with sword, and take out the acolytes until ogres spawn. Go invisible whenever you are ready to shoot at the ogres with a sniper. Patience and time works really well for this. For the hallway, use your best rocket launcher and finish the first shrieker off with your primary if it survives 2 rockets. Use invisibility to advance a little bit further into the hallway and jump on top of one of the blocks to avoid getting killed by the regular thralls. Watch out for the cursed thralls. For the deathsinger, the easiest way to do this is to cheese it. There is a way you can scale the mountains off to the side and get on top of the building where the deathsinger is. In order to damage the deathsinger, you must kill BOTH of the shriekers. Use the method from the hallway to take them out. If you do not know how to climb the mountain, look it up on YouTube. Use invisibility whenever it is necessary. When the deathsinger is dead, stay on top of the building and kill the enemies with icebreaker if you have it. Finally, crota. Use red death in the beginning as well as a gun that gives you more heavy ammo per drop. If you don't have red death, use the melee ability that restores your health with a kill. Switch to max agility and invisibility when all the enemies are dead and put on raze lighter. When you pick up all the heavy ammo that dropped, go grab the chalice. Throw a grenade at the sword bearer and finish him off with a sniper. Grab the sword and bring it on top of crota's platform from the right side. Use raze lighter's ability to down crota and damage him with the sword. Right before he gets up, use your melee ability to go invisible and down him again with raze lighter. Damage him again with the sword and go back to the room to collect your thoughts. Rinse and repeat. If you have any questions, ask me, as I have done this method to get the flawless raider achievement because you can't trust your teammates to do anything right.