Obito was never scared since Kakashi had killed Rin, but when she found out Madara was revived she had visible goosebumps.
She started planning on how to overthrow Madara, but she couldn't do it alone as she still had the cursed tag on her heart. She sought out Orochimaru to help, he was hysterical when the Uchiha asked for his help.
"You want to complete your goal and remove Madara from the picture, how optimistic is such a task?" Orochimaru chuckled.
"I cannot directly challenge Madara due to a seal on my heart, I would like to cause such a ruckus that it will force her to stop hiding in the shadows. And I want to be the one who casts the infinite Tsukuyomi." Obito stated.
"Very well, but I do require a favor from you." The snake man had a sly grin.
"Of course, there is," Obito rolled her eyes.
"I want the same power Madara has, you know how to obtain it don't you?"
"I do but it shall not be my body to give up."
"Of course not, I just need the Hashirama cells I already have spare Sharingan."
"So you want me to capture the other wood-style user, clever." Obito thought Orochimaru just wanted Sharingan, how he knew the Sharingan awakened the Rinnegan was a mystery. Madara was the only one to unlock the Rinnegan since the sage of six paths unless, of course, there was something spying on Madara.
"All right I'll help you obtain your perfect body, but how do we distract Madara?" Obito asked.
"You must attend the Five Kage summit and declare war upon the five great nations, that will thin out the herd and provide a smokescreen."
"So be it, what's one more war," Obito said to Orochimaru as she warped to the land of iron, she hid her chakra so she wouldn't be sensed as she watched the summit from the rafters.
It was all a bunch of petty politics but yet they still agreed to work together to defeat Madara, she warped to the center of the room and announced the fourth great ninja war. They were furious with the declaration of war, they even tried attacking her but she had Kamui.
Once Obito left the land of iron Zetsu told her that Nagato used Rinne rebirth on Hashirama Senju, it was perfect cause now the Akatsuki would be disbanded and Madara would most likely be too preoccupied with him.
She returned to the Rain village to move Minato out of the village, as Madara would surely kill him as retaliation for her betrayal in siding with Orochimaru instead of the ghost of the Uchiha.
To Obito's surprise he was missing from his cell, he couldn't have escaped without the help of someone else. Konan was her suspect as no one besides her and Madara knew of Minato being alive, "What are you planning, blue flower?" Obito thought to herself.
Orochimaru waited for all the strong Shinobi to leave the leaf village before sneaking inside, he snuck into Danzo's cell and took his Sharingan arm. He looked at Danzo with pity seeing the living condition he was in. He was malnourished and desperately clinging to life, a part of Orochimaru enjoyed seeing others suffer but not this. It came from his old master being as cruel as himself, the irony was not lost on him.
Days went by before Orochimaru was satisfied with the preparations for the war, he hadn't talked to Obito either. But Orochimaru made a cave into his lair for the war, he was waiting for Obito so he could reveal the plan for the war. She was changing out of her Akatsuki robe in her Kamui dimension, she was using it as a temporary living space since the Akatsuki was disbanded.
She decided to wear a blue and orange robe to mimic her old genin clothes. Obito used Kamui to Orochimaru's cave, he was waiting eagerly for her arrival.
"Tobi, I think it's time we reveal our hand to the Kage." He said.
"Surely you don't intend to fight them head-on?" Obito said knowing full well she could except for Hashirama and Madara.
Orochimaru revealed a scroll and what emerged from the scroll was twenty-three coffins much like the ones Madara and Hashirama emerged from three years ago, "Edo Tensei." She muttered.
Orochimaru had a sly smirk, "What better way to demoralize an army than by using the dead."
Orochimaru opened the coffins to reveal Deidara, Sasori, Kisame Hoshigaki, Nagato, Shisui Uchiha, Sakumo Hatake, Kushina Uzumaki, Haku Yuki, the previous seven ninja swordsmen of the mist, The second Tsuchikage, The third Kazekage, The third Raikage, The second Mizukage, Butsuma Senju, Fugaku Uchiha, and a mysterious unopened coffin.
To Obito's surprise, he reanimated Kushina, "Why resurrect a non-combative Shinobi?"
"Surely you haven't forgotten that she was the nine tails jinchuriki, after all, it was you who killed her by freeing it from her, only to have her seal it inside herself as she died," Orochimaru said matter o factly.
Obito bit her lip as the memory of Kushina's death hurt her dearly, but she powered through the pain.
"So what will you have her do in this war?" Obito asked.
"Seal her into the Gedo statue once we capture Naruto, but before then she will cause havoc using the same technique the eight tails jinchuriki does to switch between human and bijuu forms."
Obito hummed at his response, it's quite ingenious. She was anxious to see the mysterious unopened coffin, but she knew he wouldn't show her who it was if it wasn't opened like the others.
"Who's the last one you reanimated?"
"That one is an insurance policy, one that could very well change the course of the war." The snake man replied.
Obito was uneasy to his response, she didn't trust him as she shouldn't and he didn't trust her.
"When shall we start?"
Orochimaru put a chessboard down onto a rock table, tossing pieces onto it representing the Edo Tensei Shinobi.
"I think now would be perfect." He replied with an inhuman laugh.
Orochimaru studied the allied Shinobi alliance's five companies and sent the perfect combatants to each of them, Sakumo Hatake, Deidara, Sasori, Haku Yuki, and the seven ninja swordsmen fighting the fifth company, the four reanimated kage would fight the fourth company, Nagato and Shisui would fight the third company, Butsuma Senju and Fugaku Uchiha would fight the second company, and Kushina would fight the first company.
Obito planned on joining the fight but only after she captured the wood-style user Tenzo and Madara peered her head into the war. She knew Madara couldn't resist battle as it was all she talked about when Obito was stuck in Madara's cave, that and the first Hokage.
Orochimaru smiled as he moved his pieces into place, "Let the fourth great ninja war begin."
Obito left to search for Tenzo, she traveled using Kamui and found him on a giant turtle island as one of Naruto's bodyguards. She didn't want to spoil the war by capturing the nine tails immediately, this was going to be a battle for the fate of the world after all.
Obito returned to Orochimaru's cave and he wasted no time switching into Tenzo's body, once he gained control over his body he implanted two Sharingan into himself. After adjusting to the new eyes and body he tested out the Sharingan and Obito felt his chakra change as Orochimaru had completed the process and revealed his newly acquired Rinnegan, he wanted the Sharingan but this was far better to him.
Obito thought about her possibly obtaining the Rinnegan, she already had both things she needed, a Sharingan and Hashirama cells being the right side of her body. Both Madara and Orochimaru had two Sharingan when they unlocked it but she only had one.
"Has Madara shown up to battle yet?" Obito asked.
"She's engaged in battle with the First Hokage, and someone unknown has interfered," Orochimaru said.
"I take it she isn't happy about it?" Obito asked intrigued.
Orochimaru then strained his brow, "The unknown person seems to know how to teleport. Interesting, most interesting."
Obito thought that it had to be Minato-sensei, he was the only one that knows how to teleport that is alive.
"Madara is heading to the fourth division, seems like they'll get more than they bargained for." Orochimaru laughed grimly.
Obito knowing where Madara would be was going to fight a different division.
"I am going to join the fight against the first division, so no friendly fire would be appreciated."
Orochimaru ignored Obito to focus on controlling the Edo Tensei Shinobi, Obito used Kamui to warp to the shore.
She looked around and saw Kushina transforming into Kurama and destroying the front line of Shinobi single-handedly, it wasn't a battle it was a massacre. Just like it was sixteen years ago, only this time there wasn't Minato and Tobirama to stop it.
Kurama launched a tailed beast bomb decimating most of the first company, there were only a few stragglers left including the division commander Darui of the hidden cloud.
Obito saw the moment to engage something that wasn't dead, she walked up to the half-injured commander.
"So this is all the Alliance can muster, I must say I'm disappointed."
Darui turned to look at her whilst trying to launch his special lightning jutsu, but Obito just phased through it and smashed him through chunks of the beachhead.
He coughed up blood when he touched the ground, "So you're Madara, I was expecting something more flashy." He said weakly.
"The only thing I am is a bringer of death," Obito said kicking him in the stomach, "I'm sorry you're one of many to fall this early, but it is war after all." She said caving in his rib cage with her foot as he coughed up blood.
Obito cleaned off her sandal and watched as Kurama finished off the stragglers and reformed back into Kushina, Orochimaru summoned her back into her coffin. Obito was left with the stench of death, it was something she'd gotten used to since that day the mist ninja captured Rin.
Obito thought to herself of which division to attack next so she decided to go to division three because she felt the chakra of a former ally, "So it seems the traitor has shown his face, I guess we'll see who's ocular powers are superior." Obito said to herself as she warped away.