1. Try your best to score 1 arrow hit to scare off Kryll armor, then 1 arrow for damage on Raam. Make sure to fully charge so they stick. Charge them while you are ducking, center Raam on screen, press L, target, fire, and hide right away again or you won't survive his gunfire. Once he closes in, blind fire the arrows - it won't hurt you even if he is standing on top of you. Do not leave the concrete slab yet. Stay away from the edges since they are dark.
2. If you run out of arrows, start blind firing with the Lancer - the sniper rifle would be shit in this situation. He will eventually get smart and start to circle around the concrete. Timing is everything. Don't let him fire on you while you jump over the concrete slab. He doesn't fire continuously so watch for the opening. As soon as you jump over DO NOT RUN. Instead, as soon you land on the opposite side, pull back your joystick and press "A" - you slam right back into the same concrete slab but on the opposite side of Raam. Start blind firing again.
3. Start moving away from him as he will once again circle around. Make sure he hasn't sent the Kryll out and start running towards the two little stone blocks until you slightly past them. Stop running and slam into cover to the nearest stone block. STAY TO THE INSIDE WHERE THE LIGHTS SHINES and you will not get attacked. Now, Raam is forced to walk around those metal poles in the middle to get to you. Keep blindfiring with the Lancer as your arrows should be done by now. See how useless the Sniper rifle would be?
4. Draw him to your position by the stone block. Once he gets close, Swat Turn to the opposite block, slip out of cover, and start running through the middle again to the first concrete slab you started. Jump over, slam into cover, and fire away. But won't he just shoot you into pieces, you ask? Nope. Because those metal poles in the middle will block most of his bullets. From here, start blind firing again and he should be dead soon.
It's confusing, but the two little concrete blocks and those metal poles in the middle are the keys to winning. Make him walk all around everything.