Rei curiously observed as Solution finally decided to be somewhat serious. Well... serious for a spar. If she got really serious, Rei doubted the colosseum wouldn't survive the spells that would fly between them.
That said... the spar barely started but Rei already felt how overpowered he made Solution. Her defense was just disgusting and she could back it up with a lot of offensive power.
Naturally, Rei had a few sure-fire ways how to defeat her. He made her build and knew every piece of it by heart. It would also be utterly foolish to create overpowered NPC and not have a way to subdue it. Especially since he knew Solution would become real at some point.
That said, there would be no need to use one of these strategies. Rei felt he could win against Solution under the rules of the spar. It was just a matter of catching her off-guard.
Seeing that Rei is letting her start the second round, Solution decided to surprise him. In an instant, she sprang up into a run, heading straight for Rei while casting various buffs on herself, becoming a blur.
Rei answered by casting a few wordless Crowd Control spells in her path. Yesterday, he discussed with Solution how it feels for her to cast spells silently, and honestly, it wasn't that hard. Rei only wondered when will Ainz realize that fact...
Solution avoided being skewered by [Adamantine Spikes] that sprang up from the ground, jumped above the [Sticky Swamp] that appeared in her way, and sidestepped three [Earth Elementals] Rei created in attempt to slow her down. She was just a few feet away from him when she crouched, pushing herself off the ground into a jump as she sprang at Rei, striking out with her mace.
Rei leaned to the right, letting Solution's mace harmlessly sail next to him and teleported away before it could impact the ground. It was a good call considering the second the mace actually hit the ground, it cracked despite the potent reinforcement of the colosseum, sending dust and shrapnel made of earth flying all around.
While it only powerlessly bounced off of Solution, Rei was not nearly as tanky as her and it would probably warrant a few scratches if he was hit by it.
Solution furrowed her eyebrows. She knew she didn't manage to hit Rei. Before she could do anything, vines sprang from the ground and quickly entwined themselves around her arm that held her shield, her legs, and her torso, leaving only her mace arm free. One would think some vines would be no problem for someone of Solution's level. Unfortunately for her, this was one of Nature Magic eight-tier spells focused on Crowd Control, [Gaia's Binding]. The vines were extremely durable and while Solution struggled, tearing them apart, more and more vines appeared, enwrapping themselves around her body.
Seeing his chance when Solution was almost fully enwrapped in the vines, Rei quickly cast [Crushing Hellchains], making them wrap around the cocoon made of vines, squeezing it. He then sent yet another Crowd Control spell, eight-tier [Dimensional Hold] which was supposed to prevent teleportation while also slightly obstructing movement because the space in its area of effect became more condensed.
Rei didn't think this could hold Solution. It didn't have to, however. The last spell he cast on his trap was [Leeching Nature], a sixth-tier non-offensive support spell whose only purpose is to imbue the effect of draining Mana to constructs made by Nature Magic... like the vines wrapping around Solution. Rei could feel his mana pool slowly replenishing itself after he cast his last spell. It clearly worked.
He wasn't celebrating for long. Solution clearly didn't like being enwrapped like a moth. An intense white searing light burst from the openings in the vine enwrapping, charring the vines, making it incredibly easy to tear them apart with Solution's brute physical force.
This was [Holy Exuberance], a ninth-tier divine spell that caused an area of effect burning damage around the caster. Rei had to admit, it was a very good choice of spell against Nature Magic.
Getting through the Hellchains wasn't an issue for Solution either. Unlike the vines, the Hellchains were just a seventh-tier spell and while the hellfire on them resisted Solution's divine magic quite well, it couldn't hold to the superior spell for long.
Rei didn't mind. His mind was mostly preoccupied with pondering why the hellfire on the Hellchains didn't affect his vines. They were in direct contact, yet, the fire didn't burn the vines. It was indeed quite curious...
Solution finally managed to get out of her bindings, frowning. She didn't like the fact Rei was so easily capable of catching her. Not at all. It made her feel incompetent.
"I am going to cast tenth tier spell. Counter it." Rei suddenly exclaimed, making Solution's guard instantly rise.
"[Ifrit's Grudge]" Rei intoned, creating a small ball of orange energy before hurling it at Solution.
Solution recognized the spell. It was one of the easier to counter tenth-tier spells and that was most likely why Rei cast it. Unlike most tenth-tier spells, this one didn't have a massive area of effect. It started small in a ball of orange, only unleashing its might upon impact.
Solution had a very good means of countering such a spell and she realized, this was less of a spar and more of a spell-casting training.
Preparing to strike with her german mace, Solution activated one of its abilities, Magic Deflection. It wasn't a divine-class weapon for nothing, after all.
As the ball of contained orange fire got into a striking distance, Solution batted it away with her mace, sending it upwards. Thankfully, Magic Deflection caused a delay in the spell activation and [Ifrit's Grudge] high into the artificial sky of the sixth floor.
Rei was very curious about the power of the tenth-tier spells but even he was baffled when the [Ifrit's Grudge] surpassed any of his expectations and experiences from the game, coloring the entire sky of the sixth-floor orange and bathing it in intense waves of flames spreading in all directions like an ocean of rage. Rei could feel the heat on his skin, the ear-splitting roar of the spell, the potent magic contained in it... most importantly, he would have never expected the spell's area of effect. It could easily drown a city in intense flames, burning it to ash.
The waves of flames were almost upon the colosseum, when Rei cast [Yggdrasil's Protection], covering the building in a greenish-blue translucent barrier.
Fire Magic met Nature Magic clashing for dominance as the never-ending orange waves of flames tried to angrily ram their path straight through the protection of the Nature Magic and for a second, it looked as if Rei would have to cast another protective spell since the ninth-tier [Yggdrasil's Protection] was being pushed back.
Fortunately, Solution was not having it and cast [Tripple-Maximize Magic: Enhance Magic] buff on Rei's spell, helping it to keep the flames at bay.
Both Solution and Rei were somewhat surprised at the massive clash of magic happening above their heads, in small disbelief and awe that they caused it. More so for Rei as the fact this was reality and things like friendly fire and terrain damage were a thing unlike in Yggdrasil.
'That amount of energy... it came from within me?' Rei thought in bewilderment.
The entire Nazarick shook as tenth-tier spell went off inside of it, alerting the inhabitants that something... unexpected happened, causing some of the guardians and Ainz to teleport to the colosseum before their jaws fell to the ground when they saw the flames sweeping through the majority of the sixth-floor.
When after ten minutes the flames finally subsided, Rei was left flabbergasted at the damage. Most of the trees and environment on the sixth floor were burned down, leaving only the colosseum standing in the wake of his tenth-tier spell. He could only thank God there was nobody living in there.
Slumping his shoulder as he felt the narrowed gaze of Ainz on his back, Rei dejectedly thought, 'I will have to pay for the repairs, won't I?'