Jon fights against Shiryu while his clones are stopping the other Blackbeard Pirates. He needs to defeat Shiryu in a short time because his clones won't last long, especially against Teach. Jon even needs to assign 3 clones to stop Teach because this guy's power is problematic.
Right now, Jon has changed his priority to just win this war. He stops enjoying his battles now and focuses on chasing victory. Prolonging this war doesn't give him any benefit, so he wants to end this sooner.
That's why Jon becomes very serious in his fight against Shiryu. He turns his eyes from Rinnegan into Mangekyou Sharingan while blocking Shiryu's attack at a very close range. Then he looks at Shiryu's eyes and his red Magekyou Sharingan glows while spinning.
"Tsukuyomi!"
Shiryu suddenly feels the world is spinning and he gets sucked into a space whirlpool. He enters a world of lava with burning meteors falling everywhere. Shiryu tries to move, but he can't because he is nailed on a cliff that has molten lava running down the steep cliff.
He realizes it's an illusion very fast, so he is not panicking and tries to find a way out. That's until a small lava stream runs down through his left hand. Shiryu feels a very strong burning sensation on his left hand that makes him questions whether this is really an illusion.
Then some more attacks like being splashed by lava, getting hit by a falling rock, or gettinf hit by debris of falling meteors. All those things hurt him so much just like how it should be in real life. He can't even do anything and only feels the great pain on the damaged areas.
Then just when he thinks everything has ended, a giant meteor is falling straight toward him. Shiryu can only looks at it while remembering everything he's done in life. There is no guilt in his eyes, just a regret because he can't do more of those things.
The giant meteor hits him and the lava world disappears along with Shiryu. It felt so long for Shiryu in that world, but in real world, it has just been a second. Everyone sees Shiryu suddenly stops moving and then falls on his knees with empty eyes
His crewmates try to call him, but he doesn't answer. Instead of answering, Shiryu has blood dripping from his nose, ears, eyes, & mouth. Then he drops his sword and his breathing gets weaker, he is dying because of an illusion.
Jon isn't a master of illusion, but he knows how to make his illusion affects his targets' minds deeply until they feel the damage they receive in the illusion. The stress inflicted by those attacks will accumulate in their brains and it will cause real damage in their bodies.
Brain is more powerful than what people thought. It commands everything that happens in people's bodies, after all. People can die if their brains stop functioning and it can command the body to die if it's really serious. But there's no people stupid enough to do that.
Jon Genjutsu isn't very powerful just as it is. The biggest factor that can make his Genjutsu has this effect is his Conqueror Haki. This haki makes his mental attack much stronger and gives stronger effect to his opponents too. Rinnegan doesn't even help his Genjutsu as much as his Conqueror Haki.
"Another one is down, who wants to be next?"
Jon grins while holding Shiryu's head and absorbs his energy. Shiryu's energy is transfered to a fruit and it turns into a devil fruit. This is the Suke Suke Fruit that allows its user to be invisible. Shiryu dies after Jon took all his energy and he falls on his back because Jon releases him.
"Come on, guys. I thought you are an Emperor crew that wants to conquer the world. Teach, isn't your crew too weak compared to its reputation? Sigh, what do I expect from thieves who like to steal people's power. Even their Captain got his 2 devil fruits by killing an unsuspecting man and a dying old man. Such a trash crew."
Jon smirks while saying that and he approaches the Blackbeards slowly. He raises his swords before running not-so-fast toward them. The Titanic Captains are attacking him, but he evades all their attacks very easily because he can see all their attacks' trajectories.
He is coming toward Teach and attack the less-teeth man because he wants to finish this war quickly. Jon swings his swords diagonally from below, but Teach counters them using a quake punch. The collision of their attacks creates a powerful shockwave that spreads everywhere.
Jon's attack doesn't look special, but he actually coated his swords with advanced haki and high amount of chakra. The ground on Teach's side is cracking because of the quake, while on Jon's side, the cracks spread from his feet because of the pressure from his body.
The normal pirates are blown away because even the remining Titanic Captains are having difficulties standing. Jon's & Teach's clash is just that powerful, after all. Teach might look stupid, but he is strong, and Jon knows that well, that's why he decided to attack Teach now while he still has a lot of energy.
Their battle continues and Jon is overwhelming Teach in a short time. He is very fast and Teach can't follow his speed. But Teach has a way to deal with fast opponent like Jon. He covers his entire body with his Darkness power and armament haki to block Jon's attack.
Teach's darkness power acts like a cushion that absorbs the energy of Jon's attack. But it can't completely absorb the energy, that's why Teach still needs armament haki to block Jon's attacks. Teach keeps hiding like a turtle while Jon keeps attacking.
The Titanic Captains are trying to help their Admiral, but they also can't follow Jon's speed. They decide to bombard Teach because they know their attacks won't pass his darkness. That way, they might hit Jon who moves around Teach to deliver attacks.
Too bad for them though, none of their attacks hit Jon because he can see everything they do with his rinnegan. He evades them all and uses their attacks that hit Teach's darkness cloak to deliver stronger attacks at Teach. Jon is attacking again with a very fast slash, but suddenly his smells something very strong that it makes his nose hurt.
Vasco is using his Sake Sake fruit to turns the air around Jon into alcohol with a very high concentration. It doesn't make Jon drunk because he has high tolerance to poison which includes alcohol, but the super strong smell of alcohol hurts his super sensitive nose that he got as a Jinchuriki Kyuubi.
His concentration lost for a moment and it gives Teach a chance to attack him. Teach grabs his neck and lifts him up while he battles against the alcohol around him. Jon tries to burn the alcohol, but he is surprised to find out that he can't use ninjutsu.
To be precise, he can't control his chakra to use ninjutsu. Teach's Darkness Darkness Fruit can actually affect his chakra flow. It can affect even him, a non-devil fruit user by disrupting his chakra flow, making him unable to use ninjutsu.
"Take this, you red eye bastard!" Teach covers his other hand with quake power before sending a punch at Jon's chest. His crewmates have moved away because they knew what he would do. They don't want to get caught in Teach's attack range.
A very powerful Quake punch hits Jon's hands that he crosses in front of his chest to block Teach's punch. Jon can't even coat his body with haki because his chakra flow has been disrupted badly. So he can only believe in his body's toughness to face Teach's quake punch.
Jon is sent flying quite far, followed by a powerful shockwave that destroys the ground. He coughs blood, but he doesn't lose his concentration. Jon has been released by Teach, so he does his best to circulate his chakra again and covers his body with haki.
Teach's attack has damaged his body, but he managed to stop further damage by coating his whole body with haki as soon as possible. Now he can circulate his chakra normally too, so his super healing ability will start to heal his injured body.
However, Jon knows he can't drag this battle for too long because the Blackbeards have started to get used to his fighting style. He still has other tricks, but he knows it's better to end this as fast as possible. Besides, Teach's ability to seal even his power which is not a devil fruit ability is a very dangerous factor in this war.
"Fine, enough playing. It's time to be serious."