On the seventh day of Eren's entry into the tower. Nighttime!
"Screeeeeeeeeeee!"
Eren was fighting a horde of wraiths. They screeched collectively when they saw their opponent kill more of their kin with his spells.
Eren had used his go-to fire element spells against the wraith horde– fire snakes and breath of fire. The elemental reptiles had created a perimeter around him so that he could hunt the monsters with ease.
The butcher saw a group of three wraiths advancing on him while he was busy moving from another group. But he was already aware of his surroundings and wasn't panicking.
Using the fire snakes, he slowly destroyed the bodies of the wraiths in the perimeter. There were only a few wraiths present inside Eren's self-created isolated battleground. The first group consisted of the four wraiths while the one who was trying to take Eren down by surprise had three wraiths in it.
The Wraith's bodies were destroyed in groups because they had attacked and stayed together to face his assault. Soon, the spectral forms of the wraiths would appear and try to destabilize him using their screeches.
And yet Eren didn't feel like worrying. He flashed a mild smile and cast the latest spell in his repertoire. A throwable medium-range spell he never used before.
"Solid spark!"
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Compared to the last time when he was on the verge of dying, he felt at ease even when the intensity of the battle had increased. In contrast to his first day, Eren wanted to be part of more intense battles like these because it was helping him digest all his gains.
And Eren had a lot to digest and process. This was because of the rewards he had received on the fourth day of survival in the tower. He had stocked his battle points to get the rewards after looking at the list of items available and their prices in battle points.
The most expensive item among the rewards was Potion of Serenity. He had to burn two days of his battle points to get the potion. But he did it without any hesitation.
Eren had come to realize that the brat had done a huge favour for him by granting him the Potion of Serenity. Without it, Eren still would have been an almost normal ranker in terms of the spells he had. He knew he wouldn't have survived if he didn't have the fire snakes as well as the enhanced version of his defensive spell.
Of course, Eren had realized that Layla did it for her own reasons. But that didn't lessen the benefits he had received from the potion.
Layla had warned him that the potion wouldn't be as effective as the first time. With each use, the potion's efficiency would only decrease. But that didn't discourage Eren from getting it.
Eren had come to realize that the potion would be worth all his efforts even if it worked half as well as the first time. He was right on point with his prediction.
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"Solid Spark!"
Two distinct-looking lightning-element shapes started taking shape over Eren's palms. They were zig-zag in shape and were about a meter long.
Bzzzzzzt!
They buzzed like bees with various tongues of electricity dancing over them. The Sparks illuminated Eren's visage in the black night and made him as well as the lightning rods distinctly visible amid the horde of wraiths that were glowing with dark blue mana around them.
The process of creating sparks was relatively fast and easy. Eren threw both the sparks he had generated over his palms at the two groups of opponents. One was thrown at the group that had a cluster of four wraith bodies while the other was aimed at the group that had three bodies in it.
Swoosh! Swoosh!
Bzzzt!
The solid sparks flew through the air at an incredible speed. They were detonated and created a micro-domain of lightning as soon as they hit the targets.
The wraiths' spectral forms were just emerging from their destroyed bodies when the solid sparks hit them. A small, domain-like cloud of lightning was created after the detonation of the spell.
Screeeeeeee!
The wraiths' spectral forms produced another round of screech. But this time it was more of a dying scream and wasn't harmful to Eren at all. The spectral forms were destroyed when Eren fired two solid sparks at the same positions.
'Heh! Solid Spark is effective for short and medium-range attacks. Let's see what the lightning cloak does.'
The butcher thought of the lightning cloak variation of his spell that he had perfected after drinking the Potion of Serenity for the second time. He had only changed his defensive spell to that of a cloak visually before consuming the potion. The effects were relatively superficial.
But it didn't have the runes inscribed on it. The same ones the cloaks had when he first wore it during his battle in the underground dungeon.
But thanks to entering the forced ethereal state for the second time, Eren was able to identify the errors in executing his defensive lightning spell and improve on it. The spell's effects were strengthened as a result– enabling its caster to face the horde fearlessly.
Eren purposefully moved near another group of wraiths and allowed them to hit him. The first wraith used his spear on him and aimed for his heart. The impact of the spear couldn't be negated by the cloak. So he was forced to take a few steps back.
The second wraith followed that attack by directly grabbing his right arm and letting his dark blue mana do the trick. The mysterious mana spread over Eren's cloak-covered arm. It created a dense layer of dark blue ice that would feel extremely cold to the bones for a normal ranker.
The third wraith tried to injure Eren by using an old-looking flail on him imbued in dark blue mana. The ball studded in pointy metallic protrusions hit Eren's back and tried to freeze him from the point of impact.
But the butcher only smiled as he was getting thrashed about by the wraiths. That was because the injuries he was receiving from the wraiths weren't even worthy of him uttering an 'ouch'.
The cloak of lightning's mana consumption would increase after taking each injury. Mana consumption increases with the severity of the attack. That's why Eren couldn't indulge in his testing phase for longer.
Lightning element insights have been successfully tested.
Hehe!
Now it's time for me to test the only fire-element insight I haven't used in battle yet.'
Eren thought to himself and snapped his fingers as he was getting a one-sided beating from the restless wraiths.