The magic missiles quickly and accurately head for Adria, leaving behind a blue trail as the go. Adria simply swings her staff and causes a purple explosion to rapidly expand from her position, disintegrating the magic missiles caught in it.
Adria "You're too late, the preparations have been made, there is nothing you can do to stop it!"
Leah "Mother!? But why!? WHY WOULD YOU DO THIS!" she shouts, tears glistening in her eyes at the brutal betrayal.
Adria was about to reply but the charging Barbarian silenced her momentarily, she chants a spell under he breathe and taps the floor with the but of her staff, causing a purple beam to shootout and hit the Barbarian in the chest, he's shot backwards and crumbles to the floor, grasping at the smoking wound that glows an ominous purple...
Mathias scowls, "You'll not get away with this Adria! We've fought many before you, and yet even Belial and Azmodan fell!" he shouts, waving his hand and forming some sort of lightning armour to coverhim. "Leah, stay back." he says as he teleports a few meters behind Adria.
Adria could feel his magical energy fluctuating, and due to her having seen his style of combat before, she was already prepared for his teleportation. A purple sphere surround her as Mathias shoots a huge red laser at her, the laser colliding with the shield but continuously getting deflecting upwards towards the sky.
Mathias ends the spell in-order to save some magical power and raises his hand, summoning three hydra heads wreathed in lightning which sprout from the floor nearby and begin shooting lightning bolts towards Adria.
Adria matches his summon by conjuring huge golems from the nearby rubble, they stomp towards Mathias and are about to crush him into a meat paste.
*BOOM!*
A huge magical orb erupts from Mathias hands, as it hits the golems they're pulled into it as if it were a black hole, continuing on into the sky as if the Golems hadn't existed at all.
Mathias releasing a hot breath afterwards, that spell was quite taxing to use and he hadn't completely mastered it yet... Regardless, he was determined to not lose. With a shout he throws his hands into the air, summoning a tornado which rushes Adria's position.
However, with a simple wave of her hand, the tornado was dispelled, leaving Mathias dumbfounded. He shakes his head and casts a barrage of flaming lightning bolts towards Adria, but she easily fends those off too.
Adria "I've had enough playing games with you Wizard." she mutters, raising her hand in Mathias direction.
Leah "Don't!" she screams, unintentionally unleashing a bolt of dark energy at Adria who deflects it at Mathias who hits the ground like a puppet with its strings cut.
Adria bursts into crazed laughter after all her opponents were defeated, a mad look overtaking her features as she roughly grabs Leah with telekinesis, levitating her next to the Black Soul Stone that continues to pulse inside the pentagram.
Adria "Oh, don't be sad daughter... You'll become something much greater, this is why you were born after all."
Leah continues to struggle, but is no match for Adria's magic, she can only watch helplessly as the witch begins chanting and channeling dark energy from the stone into her. Her head jolts back as she screams in agony, feeling like her soul was on fire.
Tyrael can only watch in despair as the seven evils were channeled into Leah, he knew this meant the end... With all the seven evils combined their strength would be unmatched, not even heaven could stand against such power.
A minute passes and a shockwave of dark magic erupts from Leah as Adria releases her. The young woman falls to her knees, glowing with demonic energy. "I... LIVE!" she shouts, looking up and revealing her yellow slitted eyes to Tyrael.
Tyrael "No... Diablo..."
Leah stands as wispy black smoke follows her movement, she looks down at Tyrael and gives an inhuman grin towards him, "Greetings, Angel." she turns towards Adria, "And well done my faithful servant, with all the seven evils combined, I have become... The Prime Evil."
Adria kneels, "I will continue to serve thee, if you allow it my lord." she says, almost begging.
Leah nods, "Indeed, you are a valuable servant. Go, I will head to heaven to show how weak the angels truly are, wait until I call you aga-"
*CRACK!*
An ungodly sound echoes through the area, causing everyone conscious to squint and look up, the blizzard abruptly clears as a shockwave passes through the area, knocking Adria over and almost doing the same to Leah.
They're all greeted by a blinding turquoise light, once their eyes adapt to the brightness they can finally see what it is... It's... A crack? It must be thousands of miles away at this moment, but it's rapidly getting closing, the crack in space/time shoots across the sky, moving erratically and spewing strange creatures and objects wherever it goes.
Adria "My lord! We should move, whatever it is it's heading towar-" she's not able to finish her sentence as the crack passes through the area, illuminating all of them in a turquoise light before they all vanish along with the top of the keep.
...
Elsewhere :
A peasant by the name of Lennon wipes sweat from his face and rests his hand on the plow connected to the horse next to him. "Nothin' like a 'ards day work, ain't that right Bennet!" he calls to a man working on the other side of the field.
"Shut your fucking mouth and work you cunt!" they shout back angrily, having had to pick up Lennons slack as his work was extremely inefficient and lazy.
...
He shakes his head and is about to continue laboring, were it not for strange lights to appear in the sky... "Strange, I'd thought those' northern lights only came around in wintar'" he mutters to himself.
But you had something they didn't. Something no one saw... But me. Can you guess? Luck.
As always, if I missed anything please let me know.