After sparring with Goku, and pushing Goku to Super Saiyan God, Y/n resumes his meditation as Goku and Vegeta begin sparring.
Whis: You've been mediating constantly for the last month, you've barely even eaten.
Y/n: I feel fine... Well, I have this uneasy feeling, actually.
Whis: Oh?
Y/n: As if something bad is about to happen, maybe not even bad... But something big. Something I've never experienced before.
Whis then receives a call from Bulma, which he answers.
Whis: Yes, Lady Bulma?
Bulma: You picked up, great! Goku, Vegeta, and Y/n are all there. Can they hear me?
Y/n stops meditating and walks over to Whis.
Y/n: Dad and Vegeta are sparring at the moment, what's up?
Bulma: Frieza's back!
Y/n: Wha- Frieza?!
Bulma: Yeah, and he's here!
Y/n grits his teeth as Goku and Vegeta walk over.
Vegeta: So the cum stained lizard has returned?
Goku: We can get there with Instant Transmission.
Y/n: Yeah, but everyone has to raise their power first.
Bulma: Say less.
She turns to Gohan, Krillin, Tien, Roshi, Piccolo, and Yamcha.
Bulma: Raise your power as high as possible, okay?
They all nod and power up and Frieza, who was watching, smirks.
Frieza: You're summoning him, aren't you? Excellent!
After a moment, Y/n and Goku can pick up on everyone's energy and Y/n Instant Transmissions to Earth, followed by Goku and Vegeta.
Y/n had ended up a good distance away from the group, closer to Frieza.
Frieza: What...? Who the hell are you?
Y/n: I'm Son Y/n, also known as the strongest Earthling alive.
Frieza: Oh, an Earthling? You were adopted by a monkey, how adorable!
Y/n grits his teeth and goes to retort when Goku and Vegeta walk over.
Vegeta: So who fights first? I think it should be me.
Goku: No, me!
Y/n: Guys...
Vegeta: You already beat him on Namek!
Goku: That was forever ago!
Y/n: Rock paper scissors for it.
Goku: Yeah, that's fair.
Vegeta: Tch...
Y/n, Vegeta, and Goku then begin playing rock paper scissors and Frieza deadpans.
Goku: Aw, what?!
Vegeta: Scissors beats paper, Kakarot!
Y/n: And rock beats scissors, and paper beats rock. Redo.
Y/n/Goku/Vegeta: Rock, paper, scissors... Shoot!
Y/n throws scissors while Goku and Vegeta threw paper.
Y/n: I win, I fight first.
Goku: Just be careful.
Y/n nods and floats over to Frieza, a smirk on his face.
Y/n: So you came back, huh? Can't say that idea is smart, but... Here you are.
Frieza: You think you, a mere Earthling, can go toe to toe with me, Lord Frieza? And even more ridiculous, you have the audacity to act as if we're equal.
Y/n: See, I wasn't suggesting that...
Frieza: Then what are you suggesting?
Y/n: I wasn't suggesting either, I'm pretty damn sure I can beat you.
Frieza: Oh really?
Y/n: Yeah, I'm pretty confident about it.
Frieza: Then put your money where your mouth is!
Frieza rushes Y/n and lands a punch to his gut, making Y/n double over in pain as he coughs up blood.
Frieza: Ha! What? Done already?!
Y/n starts laughing and wipes blood off his lips, then smirks.
Y/n: Come on, are you serious? Who'd be afraid of you when you can't even deal significant damage to a " mere Earthling "?
Frieza slowly backs away, his eyes wide with temporary fear, but he regains his composure quickly.
Frieza: You fool, this is only my first form!
Away from the fight, Goku turns to Whis, who was sharing a sundae with Beerus.
Goku: Whis, I'm not entirely sure what's going on...
Vegeta: For once, I'm confused as much as he is.
Whis: Oh? What's confusing?
Goku: Right now, Frieza's almost twice as strong as Y/n... So what's up with Y/n barely taking damage?
Whis: It's rather simple, Y/n's training has made his Ki control much greater than before, and as such he can fight outside of his weight class even without powering up. Though, Y/n is also still capable of far more power than this. Frieza has his work cut out for him.
Vegeta: What?! Damn!
Back with Y/n and Frieza, Frieza is engulfed in a purple aura, which slowly turns gold as he powers up into his Golden form.
Frieza: Behold, Son Y/n! The ultimate evolution - Golden Frieza!
Y/n's facial expression drops and Frieza smirks.
Frieza: Perhaps you've realized your mistake now! You're no match for me!
He fires a Death Beam, but Y/n suddenly bursts into Kaioken, powering up to the max right off the bat.
Y/n: Kaioken X 100!
He dodges Frieza's attack, then rushes the tyrant, throwing several punches at him, but Frieza dodges them all before he smacks Y/n away with his tail, and Y/n is sent flying through some boulders before skidding to a halt. Frieza begins slowly walking over, and Goku goes to jump in before Beerus speaks up.
Beerus: Let him get up.
Goku: What?! That's my son, damnit! I won't let Frieza kill him!
Beerus: Have faith in your son, Goku. If what I think is happening is about to happen, then you need not worry... If I'm wrong, then you and Vegeta can interfere.
Frieza laughs maniacally and prepares a Death Beam at point blank range, it seemed Y/n would perish.
Frieza: This is even better than just killing Goku, because now he's going to watch his son die fighting his battles! Begone, worm!
He fires the Death Beam and the attack creates a huge smokescreen. Frieza crosses his arms smirking. As the smoke clears, Y/n can no longer be seen.
Frieza: And so, the killing has begun with the son of Go- HUAGH!
Frieza falls to his knees and coughs up blood as a figure in a brilliant silver aura now stood behind him, his arm extended before he slowly lowers his arm.
Frieza looks behind him and growls before quickly getting to his feet and throwing a punch at the figure, only for them to duck underneath his punch and then backflip kick him away, sending Frieza flying. The figure then stands completely still and his aura flakes off, revealing Y/n, who now had his eyes closed.
Goku: Wh-what?!
Vegeta: Impossible!
Beerus: Oh, but it isn't... The prophecy is now completely realized! First appeared a Super Saiyan God, and then the Ultra Instinct Warrior, and that warrior is Son Y/n!
Whis: Oh, this is splendid! He achieved it so quickly, I'm simply overwhelmed with joy!
Frieza, now in his Final form slowly stands up and looks up to see Y/n, whom he'd thought he killed.
Y/n: Well, Frieza... I was really expecting you to kill me. This is almost as surprising to me as it is to you.
Frieza: Wh-what is that...?!
Beerus: That, Frieza is a power even us Gods struggle to achieve. That is Ultra Instinct Omen, a technique of the gods.
Y/n: So, are you just going to stand there... Or are you going to attack me?
Frieza aims at the planet, then goes to fire a Ki blast before Y/n drop kicks him into the sky. Y/n then flies up after him before stopping him with a single finger.
Y/n: You're a really sore loser, Emperor Brat.
Frieza throws a punch at Y/n, but he dodges it.
Frieza: Rah! How dare you mock me in such a manner!
Y/n: Well, how would you like me to mock you? I take requests.
Frieza fires a point blank Death Beam at Y/n, but he flips over the attack, plucks it out of midair, and slams it into Frieza.
Y/n: Return to sender, I'd like a refund.
Frieza growls and goes to attack again when his eyes widen as an unbelievable pain racks his body. Y/n had punched clean through his chest.
Frieza: This... Is how I die...? Felled by a child of Goku?
Y/n pulls his fist out of Frieza's chest before firing a point blank, one handed Kamehameha, disintegrating him instantly.
Y/n then looks down at himself and smirks.
Y/n: Damn I'm good.