Instructions
Avoid her claw attacks. At first, the only attack she will have will involve her dashing up to you, which will not damage you by itself, and then slashing in an attempt to get you. If you step to the side of her, she will not be able to get you, and you can score a number of hits against her. When she rears up her claws, it is time to move to the side once more. This rearing process is quite evident, making her claw slashes relatively easy to dodge.
Use the Abyssal Chain to rapidly come within range of her. She will teleport a safe distance away after you have hacked some of her life away. Close the gap quickly with the Abyssal Chain, and attack her once you get in range, preferably before you hit the ground. After a few hacks, she will teleport away once again.
Run around the room when she begins to excessively teleport. She will begin to teleport wildly around the room, with the final teleport attempting to land on top of you. Be ready to get out of the way when she teleports above you. If she lands on you, this will deal a good amount of damage, so avoid this at all costs. You will more than likely not be able to land any blows on her after she lands, because she will teleport away instantly. Once in a while, she will stay in the spot and attempt another claw attack. Use this opportunity to again dash to the side of her and land some hits.
Watch for her to teleport to the center of the ceiling. When she does so, she will have a circle of red orbs around the perimeter of the room, and they will begin to drop one at a time. These orbs create explosions when they hit the ground.
Use the Abyssal Chain to grapple on to a red orb and then onto Silithia. At the first sign of these red orbs, grapple onto one of them and then grapple once more onto Silithia. A cut scene will follow where War will defeat Silithia.