No Pov
Ozpin's side charged the next day. At the beginning, everything was going as well as it could. The Atlesian team and Qrow completely drew away the Grimm, and the Beacon team got in undetected into an underground chamber. They found the hound with Summer in it, surrounded by small Grimm, Tyrian, and Hazel.
Y/N's Pov
Tyrian: "Not running this time?" He jumped at me and I drew him away from the others. I punched him and he was sent flying back outside. I went after him.
His tail kept me on my toes, but I was still easily able to take him down. I realized we had a problem. Our plan had been for Ozpin to delay Salem, but he was occupied helping take down Hazel, and Salem was nowhere to be seen. He and Summer together were almost an even match for the others. I figured our side would win, but Salem was probably on her way right now.
The only way was to do what I had been hoping to avoid.
I went back down and went straight for Hazel. I gave him everything I had, hoping to finish him before Salem got here. He was almost done, until I saw Salem coming.
The smaller Grimm were dead, and Hazel was almost done, so I teleported out and caved in the entrance with a wave of air dust. There was a hole big enough that they could still breath and had some light, but Salem wouldn't see them inside.
Yang: "What are you doing?"
Y/N: "Getting you all more time. She's here." I turned away. I felt the adrenaline coming on, allowing me to push my emotions down.
Yang: "Don't do this!"
Ruby: "Yang, come on. If we beat them faster we can help him!" I heard her reluctantly turn and go back to the battle.
There was a reason I had decided not to tell anyone about this. They were all needed to stop Salem, I was just a powerhouse that could only give them time. This was it. What my entire life, all the years of battles and experience, and all the pain had been building to this.
I turned to Salem, who still hadn't noticed me because she wasn't sure where she was hearing the fighting from. I fired an air dust wave at her. It hit and she turned to me.
Salem: "Did you think that would hurt me?"
Y/N: "No." I sheathed my sword. "That was just to get your attention." She fired a rainbow colored stream of lightning at me, but I just teleported to the other side of the valley we were in. "Wow. If you were always that quick to act, you would've won by now."
Salem: "If you wanted to die, you could have simply asked." She sent what looked like tentacles of Grimm flesh at me, which I dodged again.
Y/N: "I think we both know I can't just do that."
Salem: "This is pointless. Nothing you have can kill me."
Y/N: "You're right, I can't. But I can do what I've been doing for over 10 years. I can hurt you." She hurled a massive boulder at me. I cut it in half with a single swing.
She hovered at high speed directly at me and tried to grab me with more of the Grimm tentacles. When that didn't work, she made hands come out of the ground to try to grab me, and I responded by teleporting into the air and diving into the ground, stunning her and breaking her attack.
I pressed my advantage by drilling her until she tried to hit back, forcing me to dodge away and break off my attack. I fired dust waves of every kind at her in a effort to slow her down while I went in for another pass. She pulled back and fired more lightning at me and I had to repeatedly teleport to different locations around the battlefield until she finally let up.
Salem: "I know you're stalling. Just give this up and I will make your death quick."
Y/N: "What's the matter? Can't take down a kid?" She paused as if she was pondering something.
Salem: "In all my years, I have seen many of the unfortunate fools that Ozpin recruits to aid in his fruitless quest. But they all had one thing in common. They all feared me. In their final moments, they all were openly terrified. Even Ozpin is. But you... You taunt in the face of your own demise."
Y/N: "I've looked death in the face more times than I can even remember. You don't scare me. Honestly, you're pathetic." She sent another large boulder at that I punched with Yang's gauntlet. "Oh, did that upset you? Well, it's true. You're the most powerful human in the world, and you hide in the shadows and make others do your dirty work like a coward. You only get off your butt to do anything every couple hundred years. At least Ozpin occasionally does something himself. The only thing I've seen you do is accidentally kill your only chance at getting the Winter Maiden removing her protection from the Grimm."
She was clearly enraged as she covered the entire ground around us in lightning. I teleported into the air and slammed down on top of her. She lost concentration and fell back a few steps, and I took the opportunity to hit her as fast as I could. She still seemed to feel pain, so I figured it would work. She eventually forced me to break off.
Y/N: "And why do you do all of this? Because you lost someone thousands of years ago? Was it really that bad of a breakup? Do you know how many people have lost someone thanks to you? You're nothing but a petty child."
She sent an explosion of blinding lightning at me. I just teleported to the other side of the battlefield again.
Salem: "No matter how long this takes, you will still fail. I cannot be stopped. What do you think you can do that Ozpin has not already tried?" I had to bluff.
Y/N: "I'm just going to hurt you."
We charged at each other again. This time neither of us were holding back. I let my experience take over, unleashing everything I had. I knew it wouldn't be enough, but it didn't have to be. I didn't need to win this fight, I just had to last as long as possible.
Eventually I took a hit, and knew this was the end. I let it all out like opening the flood gates of a dam. I don't even know what happened after that. The next thing I knew, I was on the ground from sheer fatigue, my entire body in the worst pain I had ever felt.
Salem had massive gashes on her face, and there were hundreds of expired streaks of dust waves everywhere around the battlefield. Her wounds healed, but she screamed in pain from the sheer number of them.
The last thing I saw as my vision went blurry was a yellow form fly at Salem and start blasting her. Then everything went black. I felt at peace for the first time. I had done what I had to.
No Pov
After Y/N trapped himself outside with Salem, team RWBY and Ozpin jumped into action as hard as they could to try to free Summer before Salem killed Y/N. They took out Hazel fairly quickly, since Y/N had softened him up before going back outside.
That left taking out the Grimm shell around Summer. Eventually they stunned it enough for Ruby to burn it away with her eyes. Summer fell to the ground. She got up and looked disoriented. Her once silver eyes were now a greyish-purple.
Summer: "What... Where am I?" Ruby and Yang ran up and hugged her. They quickly explained what had happened and what they needed to do.
Yang: "Come on! Y/N is still out there!"
Summer: "The kid who Ozpin had working for him?"
Yang: "Yes! Come on!"
Everyone followed her outside, and as they got out they saw Salem hit Y/N, only for his eyes to start glowing and for the entire area around them to be coated in cuts for a few seconds. Salem was about to finish him afterward, until Yang flew over and punched Salem back.
The battlefield erupted in a massive display of power as they fought. Eventually they stunned Salem enough to hit her all at once. Ruby and Summer blasted her with their different forms of the silver eyes, and the group used all of their maiden powers at the same time.
When the light faded, Salem looked at herself as she disintegrated while Ozpin's soul started to leave Oscar's body. Both disappeared, leaving everyone else alone. Yang ran over to Y/N's unconscious body and picked him up.
Timeskip
The strike force pulled out after getting the signal that it was over. With Salem's death, the Grimm didn't go away, instead just becoming much less coordinated. Unfortunately, that was probably for the best, since if they disappeared then suddenly a large block of the population who were able to fight would be out of a job. It could have caused a civil war, or worse. With how things had ended, the general public would not even notice any difference in day-to-day life.
Y/N's condition was critical. His soul had almost been completely depleted by his final attack. Yang was devastated and visited him in the hospital every day. He never stirred, but his vitals persisted.
What nobody knew was that he was seeing the future he had been warned against in excruciating detail this time.