One-sided, that's how Ben's battle with Zeref turned out. An overwhelming power added with an advantage in magic allowed Ben to dominate the battle. He is much faster and stronger, and had more experience and skills.
Ben didn't give Zeref a chance to fight back and kept beating the crap out of this empire's emperor. Zeref can't hit Ben at all because his attacks always hit him first. Ben was too fast for even Zeref who can control time now.
At present Ben who didn't hold back can throw nearly a dozen punches in a second. Each of his punches were strong enough to crack Zeref's bones. Even after gaining a lot of power, Zeref still can't match Ben's power.
Zeref's immortal body was useless against Ben's Sun God Slayer Magic. Ankhsheram's Curse is breaking with every punch from Ben and he can't recover. That 400 year old curse was fading as a result of Ben's attacks.
Ben attacked Zeref mercilessly and he kept increasing his attack power. He didn't stop even though Zeref's body was covered in blood now. He knew that Zeref was still conscious because there's no way someone like him would succumb to a few punches.
Then while continuing to punch Zeref, Ben asked, "How does it feel, Zeref? Does it hurt? Is it painful? Those children who lost their parents, parents who lost their children, people who lost their loves ones and future because of you and your demons felt more pain than this. They suffered while you were thinking you did the right thing with your twisted sense of justice."
"So even if it's just a little, I will make you feel their suffering. Besides, your death is important because it will make all of those Etherious disappear, except Natsu. But I won't give you an easy death because it won't satisfy those poor souls." Ben said with an intimidating expression while he continued punching Zeref.
Ben hit every part of Zeref's body from head to toe including the balls. He didn't show this guy any mercy and destroyed everything. Those who knew Ben wouldn't be surprised by this, but those who didn't know him all that well would be terrified with his ruthlessness.
Zeref's powered up form faded away after a while and he returned to normal. He was incredible for holding on and staying in that form for a while despite the beating. Even S-Class mages would've died after receiving that beating, but he hanged on.
He can't hold on for long too because Ben was brutal. Zeref can now feel death, a very painful death that was unimaginable to him. He thought death would give him relief and peace, but it's so painful to the point that he didn't want to die.
Ben finally stopped punching him, but all of his bones have been broken, his muscles were torn apart and his skin was ripped. Blood covered his entire body and he didn't recover at all. His immortality only kept him alive, not healing his injuries one bit.
"Consider this my mercy because you won't suffer any longer. I will grant you the death that you've missed for too long." Ben said as he put his palms on Zeref's chest.
Ben's head glowed bright gold and he said, "The god was the one that tortured you, but the dragon will be the one who finishes you off. Farewell, Zeref Dragneel."
Zeref's bloody body suddenly glowed bright gold and Ben turned around to leave. Behind him, Zeref's body started to be burned by golden fire. Zeref didn't even scream because he lost all sensation in his body.
Ben left Zeref who slowly turned into ash that was carried off by the wind. The Alvarez Empire had lost it's emperor and the world lost one of it's enemies. The man who was known as the evilest mage of all time had finally died.
"That was very anti-climatic for a enemy that I feared since I was young. But that shows just how powerful I've become. Now, one more to go." Ben said while walking back to Vistarion.
Zeref's death was immediately felt by his subjects. Even if they didn't see the battle, they knew that their emperor had passed away. This is because the remaining Etherious disappeared, including Larcade who had been badly beaten by Acnologia.
The only Etherious that didn't disappear was Natsu. Ben altered Natsu's book, E.N.D, to separate his life from Zeref's. Ben also made sure that Natsu's demonic traits won't be activated, that's why he is always safe.
"This is." August said with widened eyes.
"The emperor has been defeated." Irene replied while still in her dragon form.
The beaten up Spriggan 12 were shocked by this news because it hadn't been long since Zeref attacked Ben. In that short time, he had been defeated by Ben already. Well, they were beaten up badly by Acnologia who looked like he didn't even try.
Only August, Irene, Brandish, Dimaria, Invel and Ajeel were still alive. The others had been killed by Ben and Acnologia. As for the six of them, only Irene and August didn't have a lot of injuries, while the other four were injured to the point it was questionable whether they could continue fighting or not.
Acnologia grinned because he felt Zeref's magic power disappear, but he didn't feel a great clash of magic power so he knew it must be an overwhelming one-sided battle. Zeref, a mage who even Acnologia thought was a strong mage was overwhelmed and defeated.
"A worthy dragon to slay." Acnologia excitedly said.
Ben suddenly appeared on the battlefield and looked at all of his enemies. The remaining 6 members of the Spriggan 12 look at him hatefully, but he just grinned and pointed his thumb down.
"Your emperor was a disappointment. He couldn't even put up a fight." Ben smugly said.
"And now it's your turn. Heavy World: 10,000 Times Multiplier!" Ben exclaimed as he stomped on the ground.
The gravity on the battlefield suddenly multiplied to an unimaginable degree. All 6 of the remaining Spriggan 12 including August and Irene were pinned down. Even the ground was sinking deeply. Only Acnologia could withstand the increased gravity, but even he felt himself become very heavy and he can't take off to fly.
To make it easy, Ben's multiplied gravity made the targets heavier by 10,000 times. So if someone weighed 70 kg, they became 700,000 kg or 700 tons because of the increased gravity. Not everyone had the physical strength of a dragon like Ben or Acnologia, so such a increase in weight is unbearable.
Even Irene who had turned into a dragon can't withstand it. She didn't have a lot of physical strength to withstand her multiplied weight. Her magic also can't help her counter 10,000 times the gravity and the biggest problem was the Gravity Magic disrupted her magic control.
The same thing happened to the other 5 remaining members of the Spriggan 12 who had their magic control disrupted. They also feel pain all over their body because of the gravity and they feel like they will be crushed. Blood even started to flow out of their nostrils, mouth, ear holes and even eyes because their blood vessels burst.
The 6 remaining members of the Spriggan 12 look at him hatefully, so Ben said, "What? Do you think it's unfair for me to use this level of magic after you were beaten up by someone else? Well, do you think it's fair for a whole empire to fight one man? Or are you angry that I killed your beloved emperor? Hey, this is war and he's the one that challenged me. He should be expecting to die at my hands and so should you guys."
Ben raised his right hand to the sky and created a massive black-red-gold sun ball. The sun ball was so hot that it felt like it was descending to Earthland. The suffering of the Spriggan 12 increased because they can't do anything right now.
But suddenly Acnologia struck the massive sun ball with his dragon roar. He couldn't withstand the sun ball's heat, so he destroyed it. The impact between Acnologia's dragon roar and Ben's sun ball was massive.
It created a explosion that spread the heat and shock wave everywhere. The Spriggan 12 who were close to the clash were affected the most. They were sent flying far away because the Gravity Magic suddenly disappeared.
Even the Spriggan 12 took a lot of damage from the impact, showing how powerful that short clash was. The strong shock wave even damaged the capital city, Vistarion, and the heat killed many of the remaining soldiers. Vistarion was completely destroyed even though the clash didn't take place in the city.
"What's this, Acnologia? You don't want me to kill them?" Ben asked with a grin.
Ben grinned because he knew that Acnologia destroyed the sun ball. After all, it's too hot. Even Acnologia was taking damage from the sun ball's heat because it contained Sun Dragon Slayer Magic. Acnologia had a high magic resistance, but the heat from Ben's magic was too unbearable even for him.
Ben grinned and said, "It seems I have a better chance than I thought."