Game of Throne Season 8 Theory

Jamie is convinced by Tyrion to join forces with Danys army. Cersei loses another child and after knowing of Jamies betrayal she goes completely insane ordering the closure of  Kingslanding and its filling it with Wildfire, like Aerys the Mad once did. She intends to burn down the entire city with everyone inside it.

Jaime and Tyrion travel to Kslanding to try and convince her to join forces with Dany. They arrive and talk to her.. She refuses and the Mountian engages Jaime in a fight. Jamie loses but Cersei doesnt allow the Kingsguard to kill him. While trying to soothe Jamies wounds Jamie grabs her with his goldenhand and strangles her eventually  killing her. Tyrion kills Qyburn.

Jon is elected King of Westeros and Dany orders the Wildfire to be spread all over the Reach as a last case scenario in case the Others armies breach trough their defenses.

Greyworm the Unsullied and the Hound defend Castle Black alongside the Watch and Wildlings which eventually falls to the Others. Edd and GWorm are killed.

Arya Sansa Brienne and the armies of the North fight the dead at Winterfell but are also beaten by the Armies of the White Walkers. Bronn, Podrick die in battle, Brienne is wounded but manage to escape with Arya. Sansa sacrifices herself to fight off a Giant who was after them and ends up killed. Arya is heartbroken and Brienne shocked cause she couldnt help.

The NK invades Pyke and fights Euron 1 v 1 He hits Euron but his armor and Axe are Valyrian Steel. Euron manages to strike a blow to the NK who bleeds blue blood but isnt killed.
Pyke is overwhelmed by wights and Euron manages to escape with his fleet to meet with Danys army at the reach. He tells them the NK can't be killed by Valyrian Steel alone.

The Vale defended by the Knights of the Vale, Martell Tarly, and Baratheon armies fall to the wights who swarm from every mountainside and the ones who survive retreat to Wolfswood.

 Melisandre retuns and along Beric make a final ritual sacrificing themselves to burn the Wolfswoods killing 80% of NKs wights army with it.

Its Midday and as the dead march  so the Sun fades. NK uses Viserion to destroy the entire Dothraki horde defending the reach, the ones who live scatter. Dany joins the battle riding Drogon while Bran controls Rhaegal. Jamie and Tyrion arrive at the battlefield.

Bran talks to the NK in a vision and asks him why he was trying to kill Men. {reason unexplained in the leak}

Alongside Jon Snow Jamie Tyrion, Tormund and Jorah Dany joins the fight at the Reach. After besting Drogon outta the sky Night King sends Undead Viserion away from battle to find Bran whos being protected by Sam at the God's Eye.

Viserion arrives at the God's Eye and while almost killing Bran Samwell manages to strike a fatal blow at the dragon with Heartsbane killing it (yep LOL).

Drogon falls throwing Dany far away from his reach. NK arrives to kill her Tormund intervenes and is killed by the NK who raises him as a Wight.

Jorah carries Dany to safety but is tracked by the NK and tells Dany to pull his sword into his chest killing him and giving birth to Lightbringer. She cries cause she finds out she loves him. Jon arrives fight Tormund and best killing him. Jamie and Tyrion are holding the rest of the WW and wights left at the Reach with whats left of the armies of Westeros.

NK arrives at Dany's and stabs her with a Frost spear. Drogon a d Rhaegal let loose a screech and move away from battle. Bran loses control of Rhaegal. Jon arrives, she looks at the flaming sword and Jon reaches out to Lightbringer weilding it. NK moves to Jon and they engage in an epic fight.

Meanwhile in the field Tyrion reaches to Rhaegal whos in pain cause of the bond with Dany and soothes him, which surprisingly accepts him and then he mounts and rides Rhaegal into battle alongside Drogon controlled by Bran and sets aflame wights and wws from above. Still they are losing the battle.

NK moves to Jon and they engage in an epic fight at Dany's fall place. NK ends up besting Jon and when he's about to strike the final blow Jamie Lannister arrives and pulls the magic dragonglass outta NK's chest with his Goldenhand Jon sees the opportunity and uses reformed Lightbringer to strike a finishing blow into the weakened NKs heart. NK falls and loses control of his army who just crumbles, falls and wither away all over the fields..

 NK returns to his human form and when he rises hes met by Drogon and Tyrion riding Rhaegal who burn him to oblivion.
Jon goes to Dany and sees her mortally wounded. She says he's gonna be a good king.. Jon cries and kisses her as she dies in his arms..