(Some elements come from Undertale/Glitchtale)(Evil and op OC's recommended) Pov: You killed his friend while fighting

Kioru: Welp I'm f**king dead. *runs off* (chase me bro)

(btw when you see this =) it means: *his eyes fill up with bright red)
*He glares at you*
???: You shall perish
=)
*A knife appears in his hand*
*He teleports infront of you*
*He does a combo of hits that are so fast you can't even think about what's going on*
*He hits you with the final hit and you go flying away serveral meters*

*Icy giggles*
Icy: Oopsies~

(btw when you see this =) it means: *his eyes fill up with bright red)
*He glares at you*
???: You shall perish
=)
*A knife appears in his hand*
*He teleports infront of you*
*He does a combo of hits that are so fast you can't even think about what's going on*
*He hits you with the final hit and you go flying away serveral meters*

Icy: Hehe... Finally you're taking this seriously. *they stand back up* Lets go.
*Icy summons in a Devilsknife lookalike and dashes back in*

*he dashes towards him, making their blades collide*

*Icy suddenly drops to the ground, ducking under his knife and drop kicking him*

*he slams his knife against him*
*It creates a shockwave that pushes both away*
*His eyes glow bright red*
*He swings his blade*
*He switched to DETERMINATION !*
*His blade turned red*

*Icy merely observes*

(pro tip, he cannot be killed in this stage lol, and his attacks cannot be deflected)

(I'm not gonna metagame. Icy's a villain, a prick, an asshole, but they will not metagame)

(wth is metagame)

(usually a dungeons and dragons term, but it means to (role)play with knowledge that you know, but your character doesn't)

(he knows his abilities very well)

(which one?)

(pretty much all of em)

(yeah ur OC does, but i cant say Icy knows your oc's abilities well)

(welp, if she attacks, she will notice)
*He teleports behind you*

*Icy feels his presence behind them, and turns around, playing defensive*

*he strikes dashing from every corner*
*You have lots of cuts*

*Icy's bleeding out and glitching ever so slightly, and they raise an arm. Similar to what Undyne does, a huge amount of spears come flying in from behind, hitting him. Presuming from what you've told me, he's basically unharmed*

(he can be harmed, but with determination he can survive)
*Struggles to get up*
???: You'll have to try harder!
*His eyes become black*
*He swings his blade*
*He switched to HATE*
*His blade became black*
(This phase, he can die, and you can deflect his attacks, but the attacks are extremely power, your oc know it because she can feel a great power)

(Understood)
*Icy whistles as they step back*
Icy: Ooh~ Someone's mad
*Devilsknife and Icy seem to warp, Devilsknife growing an extra blade on the bottom, while the air behind Icy distorts, making it seem like she has wings* (Imagine these wings to be something like the ones you see on Marx in Kirby: Super Star, but it's glitchy and transparent)

???: Do you know, where all this hate comes from? Do you realise you signed your destiny?
*He slowly walks towards you*
???: Do you think it will be easy?
*His blade seems powerful*
*Icy thinks its best not to get cut by it*
*Icy's agility grew!*
*Icy's defense grew!*
*???'s attack grew alot!*
(By agility it means, you can D O D G E most attacks)

Mono: That was tough...

(btw when you see this =) it means: *his eyes fill up with bright red)
*He glares at you*
???: You shall perish
=)
*A knife appears in his hand*
*He teleports infront of you*
*He does a combo of hits that are so fast you can't even think about what's going on*
*He hits you with the final hit and you go flying away serveral meters*

Mono: An edgy guy huh?
*His hands glow purple and he launches a barrage of purple energy blasts at them*

*dosent react*
???: This battle has been played multiple times, mabye i should start with HATE....
*His knife becomes black*

Mono: You're stronger than I anticipated.
*A purple gas begins to flow out from his clothes*
I'd be careful if I were you.

*he strikes repeatedly the air*
*Black curves go flying to you, they all hit, your stunned for a few seconds*
???: I showed you my HATE, now i will show you my DETERMINATION
*He swings his blade*
*His eyes glow bright red*
*He switched to DETERMINATION !*
*His blade became red*

Mono: *The gas covers Mono's whole body and he stands still*

(pro tip, do not try to kill him in the determination stage, it's impossible)
*He strikes you multiple times*

Mono: *The blade goes through the gas*
*Mono is I suddenly behind them and goes to sweep their leg*

*he backs away swinging his knife creating shockwaves to push you away*
*His eyes are filled with darkness*
*He swings his blade*
*He switched to HATE*
*His blade became black*
*He strikes the air, creating a black shockwave, pushing the gas away*

Mono: *He shoots out the gas from the palms of his hands with the intent of blinding and throws his knife at them*

*he grabs the knife right before it hits his face*
*He raise his black knife and it creates a black tentical, grabbing you by the neck*
*He flings you behind him, slamming you into the ground*

Mono: Breathe it in...
*He covers a large area with the gas and hides within it*

*he strikes the air*
*It creates a black shockwave, pushing the gas away*

Mono: *He suddenly reappears behind them and goes to shoot as much gas into them as possible*

(Pro tip, you cannot kill him in the DETERMINATION stage)
(Pro tip 2, you can deflect HATE attacks)
(Pro tip 3, you cannot deflect DETERMINATION attacks)
*His eyes fill with bright red*
*He swings his blade*
*He switched to DETERMINATION !*
*His blade turned red*

Mono: *He ducks as quick as possible and conceals himself in the gas again*

Heather: *breathing hard and goes back into human form*

(btw when you see this =) it means: *his eyes fill up with bright red)
*He glares at you*
???: You shall perish
=)
*A knife appears in his hand*
*He teleports infront of you*
*He does a combo of hits that are so fast you can't even think about what's going on*
*He hits you with the final hit and you go flying away serveral meters*

Heather: "Woah..." *shakes her head* "Can't say I didn't deserve that..."

*he walks towards you slowly*
*His knife becomes bright red and around it there's a dark red aura*

Heather: "Anything for the others...I won't let them down again..." *they stand up and pull out a dagger of their own*
ah crap i keep forgetting their agender ahhh))

*he points his knife towards you*
*Suddenly a big red beam dashes towards you* *you have little time to react*

Heather: *ducks* "Listen. I did what I came for and I have to get back home. Maybe another time?"

???: I'll show you my DETERMINATION
*he strikes at you multiple times*

Heather: *sighs* "Well, this sucks." *goes into nightmare form and counterattacks. They get behind him and rakes their claws down his back*

*he kicks you away*
*He swings his blade*
*His eyes are filled with darkness*
*He switched to HATE*
*His blade is black*
*He strikes you*
*You slowly take damage*

Heather: *growls and goes straight for him, sinking their teeth deep into his left arm*

*he grabs you and slams you on the ground, prepares his knife and stabs you, a black beam comes out*
*The a shockwave pushes him away*
*Your power has been drained, you still have some*
*He dashes towards you, going through you, for a moment, nothing but then, the pain of 1000000 strikes hits you*
=)
*He turns around*
*His eyes fill with bright pink*
*He swings his blade*
*He switched to FEAR !*
*His blade became Pink*
(Pro tip, these type of attacks cannot be dodged, but you can try to make the effects slightly less powerful)
(Pro tip 2, you can deflect HATE attacks)
(Pro tip 3, you cannot deflect DETERMINATION attacks)

ok))
Heather: *flickering in and out of nightmare form* "Oh, you'll pay for that one."

*he strikes your arm*
*Suddenly you are scared*

Heather: "What...What are you?"

*he looks at you*
*He strikes your face*
???: YOUR WORST NIGHTMARE

Heather: *grabs his rist and swipes his leg* "Not a good answer. I'm still more afraid of the others than I could be of you."

*he recoves*
*He strikes you in the chest*
???: Well let's see these others you fear of!
*Everything goes black*
(Here you need to fill in the gaps, your oc has his fears, only you know them)

Heather: *flashback time* "I swear, I did everything I could! A-And only three got away! We did pretty good!"
???: "Pretty good, hm? Well, three still escaped. And YOU failed to stop them. Is this just some game to you?"
Heather: "YOU'RE THE ONE THAT TREATS IT LIKE A GAME! I JUST WANT TO GO HOME!"
???: *grabs Heather's arm and drives a blade into their side* "You know you can't go back. You're not human anymore, and you'd never survive out there. Even I wouldn't last long."
Heather: "You're insane...After everything you've done...You talk about us being monsters. But you...You killed your brother and lured people to your experiments. After all that, you have no right to say I'm not human."
???: *sighs* "Well, you failed. And I have no use for you now." *pulls out the knife and walks away*
Heather: "I-I swear, I can do better. Send me after them now! Those kids won't get away this time!"
???: "Fine, but don't come back until you've killed all of them."

???: Oh, i see
*He morphs into the guy in the flashback*
???: You failed, you failed everyone

Heather: "..."