The cannon fodder, the demons that protected the fortress, all charged towards Kayn, trying to suppress their fears with their numbers.
However, the second the earth demon left the battlefield and Kayn placed his full attention on them, they soon realized how much of a fool they were.
With the cannon fodder grouping up together, it took Kayn only a single spell to decimate multiples of them.
If a single bullet spell didn't kill them in the first round of attack, then they would at least be gravely wounded and their bodies half frozen.
With that, the second round of bullets finished the job as two sets of spells easily killed more than 6 demons in one go.
And Kayn got four arms. Which means that he could kill 12 demons every time his arms cast the ice bullet spell.
By the time the cannon fodder got close enough to him, Kayn just borrowed a page from the ice demon's spell and created an ice pillar on his own, a thick one that wasn't easily destroyed by ordinary demons.
Without moving a single step from his ice pillar, and not even flying to move around or dodge the demons' attacks, Kayn just shot his spells and cast a defensive magic if needed, to deal with dozens of demons at once.
'Thanks to a demon's unfair mana situation, this really felt like an easy farming game.'
By the time half of the cannon fodder had stopped moving, their bodies unmoving either to a hole in their heads or just frozen by the ice mana, the rest of the cannon fodder began to stop in their tracks.
They knew now that the superior numbers that they thought would overwhelm Kayn meant nothing to his icy spells.
Whether it was a physically strong demon that could tear limbs apart when it got close or an agile flying one, Kayn dealt with them all without moving a single step from his ice pillar.
And that action told the demons that they would just be throwing their lives away if they did try to continue chasing after Kayn.
Seeing that the demons finally realized that they were giving their souls to him for free, and they didn't continue trying to fight him, Kayn finally looked back at the fortress, one that seemed to have been reinforced even more by the earth demon.
More walls were added, and the gate was now unopenable, glued by earth to the walls beside it.
'That's one quick decision-making! I guess demons really do value their own life much more than everyone else's!
Well, that fortress would still not be enough to stop me though…'
Kayn then cast another spell, one that he once again stole from the ice demon, but then modified a little.
"Fortified Ice Spear."
In terms of casting other spells, one needed to know what kind of image and intention the caster used when using the spell, and a spell like the rigid ice spear was easy enough for Kayn to figure out.
Using the same amount of mana as the ordinary ice spear spell, Kayn just imagined the ice spears to combine with each other, fortifying their structure, making them tougher and stronger.
And instead of creating three rigid ice spears, Kayn adjusted the spell so that it would only create one ice spear that was the combination of all the ice spears that would ordinarily appear in the ice spear spell.
Seeing the thick fortress wall made of earth, Kayn thought that a single powerful ice spear would be more useful than multiple weaker ones.
And with four hands casting the spell, the supposedly singular projectile became four instead.
The four fortified ice spears flew through the air with the same speed as the ice bullets, preventing any demons who had been caught in fear from reacting in time.
The ice spears crashed against the thick walls of earth, producing loud bangs that made the demons in the area tremble even more, and sending a force large enough for the first layers of defense of the fortress to crumble.
And just like the rigid ice spears that the ice demon used, the fortified ice spears also remained in the world after being cast, just lying silently on the rubble that used to be earthen walls.
'They must be too panicked to do anything funny with that attack, I get a little more time for some harvesting!'
For the first time ever since attacking the cannon fodder demons, Kayn finally moved for the first time as he cast the self-strengthening spell again to fly and collect the souls of the demons.
Kayn gathered more than a dozen souls in one go, strengthening his body even more as he felt more mana coursing through his body.
'I should really do this more often… This is like a get-rich-quick scheme that actually worked!
All the cannon fodder demons have retreated deep behind the fortress, ignoring their prior order from the earth demon to go and execute Kayn.
The earth demon saw this, but he didn't lash out. He himself knew that trying to fight Kayn was a death sentence for anyone who was foolish enough to try.
They were in constant stress as they saw Kayn ripped out the souls of the fallen demon, not being able to do anything as Kayn did as he pleased.
And their hearts almost got out of their chest when they heard the ice demon shout, "If you're not coming, then I will!"
Kayn then flew up, his four arms opening their palms and casting fortified ice spears repeatedly, throwing the ice spears at the fortress.
More earth walls were built by the earth demon, but they all were destroyed the second the fortified ice spears reached them.
As more and more ice spears appeared and the earth demon realized that his defense meant nothing, he finally decided,
"Fire the signal!"
Hearing the command, 5 demons then ran towards the center of the fortress, into a secluded room where a small pedestal made out of stone, carved in runes, was standing in the middle of the room.
The 5 demons then surrounded the pedestal, pouring out all the mana that their body had into the pedestal.
Their mana would soon regenerate fully in seconds, but the pedestal absorbed more mana than their heart could regenerate in seconds, making it only possible for 5 demons with average strength to activate it.
The pedestal then glowed darkly with demonic mana before it shot all the mana upward, through the ceiling, and straight into the high air above.
When the dark light shot above, Kayn stopped his casting for a second as he felt the bundle of a massive amount of mana fly into the sky.
When it reached a certain distance away from the ground, the bundle of mana dispersed into all directions, acting like some sort of solar flare.
Realizing that his underlings had successfully done it, the earth demon's tense expression relaxed a little as he smiled at the flying ice demon.
"You better surrender yourself while you still can! With that beacon, all of the demons from the other fortresses near this one will come and reinforce us!"