Seth (POV)
I take off immediately breaking the sound barrier in an instant. I ram right into the flat of his sword headfirst and drive us both out into the middle of the ocean. He shoved me off and spins inward and nails me with a back elbow. He spins back around has his sword glows.
Killian- Phoenix God: Flame Slasher!
I cover myself with my wings to absorb the attack but as the attack made contact, an immediate explosion ensued and I was sent careening back to the middle of the island leaving a trail of destruction in my wake.
Killian (POV)
Killian- Hmph. He's nowhere near done. Here he comes now.
Seth- (ADF) Holy Dragon: Roar!!!
A big blast of his dragon slayer magic comes right for me. I use my spectral Phoenix wings to move to the side to avoid it.
Seth (ADF)- Behind you, you bitch
I turn around quickly turn around and swing my sword only for it to be kicked out of my hand and a uppercut to my jaw that sends me skyward. Seth follows me up and hovers a little bit away from me.
Killian- So you want to throw hands huh? Fine by me. I'll show you the difference in power and skill between you and I.
Both our hands get covered in our respective Magic's and we fly towards each other and clash. Both our momentum's send us past each other and we quickly turn around to clash once more. He goes for a low kick but I front flip over it and nail him in the mouth with a right that sends him sailing.
Killian- Phoenix God: Fire Bomb Domino Effect!!
Little orbs of my fire fill up the sky around Seth. They start to flicker and one by one they explode around him creating one giant explosion that separates the water in the ocean below.

Out of the smoke falls Seth as he crash lands in the ocean floor. The water eventually rushes back in and covers him completely.
Killian- That's it? That's really all that you have? Oh hell nah. You better not be drowning. Matter of fact-
I divebomb to the ocean and breach the underwater. I make it to the ocean floor but don't see the fool.
Killian *mind*- Now where can this bitch be?
I focus in on the powerful magic pressure that fills this area and look only to have two feet land on my face and drive me into the ocean floor creating a crater.
Seth (ADF)- Holy Dragon: Seal Of Vengeance!
A symbol appears on my chest and glows

Killian- What the-
Seth snaps his fingers and the symbol along with me explode.

I sink down to the new sea floor thanks to the explosion's remapping of the landscape. Luckily for me, it unearthed a underwater volcano fire pit.

Seth (ADF)- You're finished.
Killian- That's what you think. I'm surprised you're still able to hold that form. I mean look at you. You're bleeding from everywhere, your clothes are all but ripped to shit, and did you forget that I have the same magic as you bitch!!
Death God: False Hope!
His eyes go big as I fire off a blast.

He takes the blast head on and it sends him out of the ocean and into the stratosphere. With him gone, I turn to the fire pit and fall in. The molten lava overtakes me as gain more power from it. I finish restoring my power and head back to Seth.
Seth (POV)
The blast dies down once I hit the stratosphere.
Seth *mind*- Damn it! How does he still have strength?! That was one of my strongest spells I had and he took directly and still lived. What will it take? With me almost out of energy, I need to put him away fast.
Something grabs the back of my neck and a hand goes through my back and out my front. My body shakes and I look down to see the arm of Killian.
Killian- Should've kept your guard up.
He yanks his arm out and let's me fall.
Killian- Phoenix God: Black Phoenix.
From his being comes a big black flame Phoenix.

It instantly overtakes me and continuously burns me in the 3rd degree as I crash land back on Tenrou Island. With a little luck, I landed in river which put the flames out. Still with the gapping hole in my body, I got my beaten, broken, and very bloody body up to it's feet and I fly back up into the sky to confront Killian.
Killian- So you're still alive. I must say, you are very hard to kill for a fake Death God Slayer. This is the fight I wanted so I must thank you for that but........I'm gonna have to incinerate you along with the rest of Fairy Tail. Phoenix God: Descent Of Venus!
What starts as a small fireball from his finger quickly grows in size and fills up the entire sky.

Seth (ADF)- Oh shit! Everyone's gonna die.
I turn back and fly towards the island with the attack right up on me. I get above the island in a hurry.
Seth (ADF)- Holy Dragon Secret Art: Grand Magic Holy Sanctuary!!
The entire island except gets encased in my magical energy shield.
Like this

I turn around only in time to see the the big sphere of fire a few yards from me. I stretch out my arms and wings and catch the ball. The momentum of the ball forces me up against my own shield and Killian comes around to observe his handy work.
Killian- Still holding on I see. Didn't expect you last this long. Well why don't we try this? Let's see how long you hold that sphere and a meteor shower at the same time!
Seth (ADF)- What?!!!
Killian- Phoenix God Sacred Art: Phoenix Sage Fire Meteor Shower!!!!
The sky turns grey as a giant symbol appears in the sky.

Out of that symbol comes a bunch of of meteors plus one giant one.

Seth (ADF)- Dear god. This.......this is how I die.
The smaller meteors smack the shield I have over the island but the giant one hits the giant fire sphere I'm holding and causes a massive explosion that you could probably see from space and then everything goes black.

Timeskip
I surprisingly wake. The sky's dark and rainy and I'm before Master Mavis's grave. My body is in one piece but it's totally obliterated.

Seth- I lost huh? Killian won. God damn it! If only I was stronger! I know I'm stronger than that bastard! If only I didn't have the restra-..........the restraints. (Sigh) Master Makarov..no.......Dad, if you can somehow hear me, please remove the this seal placed upon me so that I protect the everyone and defeat the evil upon us.
My call for help goes unanswered.
Seth- It....didn't.....work.......We.....really.......are screwed.
I lay there and wallow in defeat until Master Mavis's grave lights up.
Seth- What in the hell?
From the glowing tombstone manifests Master Mavis Vermillion; the first master of Fairy Tail.

Seth- Master Mavis?
Mavis- Sweet sweet child, look at what those Grimoire Heart people did to you. This cannot stand. I have heard your cry for help and as the first master, I have answered it. I have watched your journey Seth Alighieri. Even from beyond the grave. Your journey will not end here my sweet boy.
She walks over to me and places her hand on my guild mark in the center of my chest. It begins to glow and a new mark of fairy tail takes it's place.

I instantly feel a power I haven't felt in the longest time course through me. The island, ocean, and pretty much everything else begins to shake as pillar of purple light shoots into the sky.
Mavis- I have undone the seal. You are now ready. Go and protect Fairy Tail. I believe in you.
Killian (POV)
Almost to the island to destroy everyone a just as I get above it, the sky begins to go crazy as lightning flashes everywhere and waterspouts pop up left and right.

Everything begins to shake and I mean everything starts to shake. Then a pillar of purple light shoots out into the sky from the middle of the island.
Killian- What the fuck? This power, I've never felt anything like this before. It.....terrifies me.
The pillar of purple light turns gets more intense and more violent and then suddenly it stops and blows all the clouds away.

In its place I see something I've never seen before.

Killian- Well well well.........things just got a whole lot interesting didn't it? This should be fun.
Indigo: That's the end of this one. Hopefully you guys enjoyed it. Later indigo fam. Peace.