Eric kept diving deeper.

  As a skeleton, Eric didn't feel hunger or thirst, so he didn't need to stop for food—only for necessary breaks.

  In front of the passage between the tenth and eleventh levels, Eric decided to take a breather. The battle with the goblins had drained a lot of his mana, and he needed to wait for it to recharge.

  But even while waiting for his mana to recover, Eric didn't just sit around. He took out a book from his coat, leaned against the stone wall, and started reading it carefully.

  The flames in his eye sockets flickered, getting bigger and smaller, like he was really thinking hard.

  The book he was reading was the Comprehensive Guide to First-Tier Elemental Magic he had gotten from the guild. It detailed common first-tier spells.

  Eric was an elemental mage among first-tier mages, but to be precise, he didn't actually use first-tier magic. The spells he cast were based on his racial abilities to manipulate raw elements.

  Right now, he was studying the first-tier elemental spell "Fireball."

  It was the most basic first-tier spell, usually the first one an elemental mage would learn. It was super common, but that was because it was super useful.

  Short incantation, quick casting, and decent power.

  All you had to do was say "Fireball" in the ancient magical language. It was the go-to spell for first-tier elemental mages.

  Most elemental mages would specialize in one element due to energy constraints, but Eric decided to cover all four.

  "So this is how the magic circle is formed," he muttered quietly.

  "Ah, I see. Connecting the mana here and here really does make it stronger."

  He slowly raised his hand and tried to channel the magic according to the diagrams and notes in the book.

  "Fireball!" (in ancient magical language)

  The arcane syllables rolled off his tongue, and a crimson magic circle formed in his open palm. Then, a burst of fireball shot out, hit the stone wall, and exploded. It was way more powerful than just crudely forming a ball of fire and throwing it.

  "Got it on the first try. Must be a racial advantage," he thought.

  "But the accuracy could be better." Eric reviewed the magic book again and raised his hand once more.

  "First-tier elemental magic, Fireball!"

  This time, he visualized the trajectory in his mind and carefully controlled the mana. The fireball hit the target dead-on.

  "Nice shot. Not bad."

  After practicing the "Fireball" spell a few more times without firing it to save mana, Eric felt a bit more confident and turned the page.

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  "First-tier magic, Water Arrow!"

  "First-tier magic, Earth Bullet!"

  "First-tier magic, Wind Blade!"

  After trying out the most basic and commonly used spells of the four elements, he carefully put the magic book away and stood up.

  In his opinion, these spells still lacked something. They were too rigid and not very practical. For example, mixing the first-tier spell "Earth Bullet" with water elements and shooting it into someone's eyes seemed way more useful than just splashing mud in their face.

  Or breaking down "Earth Bullet" into sand and throwing it in their eyes. In combat, blinding the opponent was super important. Maybe the mages in this world had some kind of snobbish pride and didn't like using such "lowly" spells.

  Eric casually thought about it and then shrugged it off. He walked towards the passage from the tenth to the eleventh level underground. Beyond this point were monsters above Level 10, and the danger level shot way up. He had to be extra careful and not let his guard down.

  He disappeared into the dark passage.

  "Tap tap tap."

  The sound of his footsteps echoed as he descended. Level eleven underground.

  The temperature spiked all of a sudden. The ground and walls were bone-dry. For regular adventurers, this heat would be pretty torturous.

  But Eric, being a skeleton, didn't care about hot or cold. Plus, he had [Elemental Resistance], so this level of heat was nothing to him. He felt the hot wind blowing in his face and kept walking deeper.

  According to the intel, this level was mainly inhabited by red lizards. They could manipulate fire to some extent and were super agile.

  Eric soon got a glimpse of the legendary fire lizard. It was more like a crocodile-sized lizard, kind of like a Komodo dragon.

  "Hisssss!"

  Seeing Eric, it let out an aggressive hiss, opened its mouth, and gathered fire elements inside.

  "Jeez, what a bad temper!"

  Eric complained, but he was actually relieved because it seemed pretty dumb.

  "Whoosh!"

  A fireball streaked towards Eric. Watching the fireball, Eric gripped his staff, and the spell from the magic book popped into his head.

  So, he took out the book. There was no other way.

  Defensive magic was complicated because it involved maintaining mana, and it wasn't the kind of spell you could just memorize in a few minutes.

  With [Agility], he dodged the fireball, held the magic book in one hand, and raised his staff with the other. He looked like a legit mage.

  "First-tier magic, Water Wall!"

  The magic stone at the top of the staff glowed with a beautiful azure light, and a disc-shaped magic circle quickly formed on top.

  Water gathered in the air and formed a flowing water wall. The fireball from the fire lizard was easily blocked, just raising a wisp of steam.

  The fire lizard was stunned. Then, it decided to go around the water wall.

  "..." Eric quickly flipped to the next page of the magic book.

  "Let's see, like this, like this..." He awkwardly manipulated the water wall to move. But his clumsy control was no match for the fire lizard's nimble movements.

  The water wall didn't block a single fireball after the first one.

  "Ugh, forget this magic!"

  Eric closed the magic book, gripped his staff tightly, and charged forward, leaving a dark blur on the spot.

  "Hisssss!"

  The fire lizard spat out a fireball. Facing the incoming fireball, Eric tightened his grip on the staff. He gathered wind magic into a vortex, covered it on the staff, and with [Giant Strength], he swung it hard at the fireball.

  The fireball exploded in mid-air, scattering into streams of flames.

  Eric didn't slow down at all and charged straight at the fire lizard, raising his staff. "Die!"

  There was no way to dodge. The fire lizard felt like it was locked in place.

  The staff turned into a blur and struck the lizard's head.

  "Boom!"

  The lizard's head exploded.

  [Ding, Fire Lizard Lv11 defeated, +150 experience]

  "Magic still feels more natural to use this way," Eric thought. The spells in the magic book didn't really suit him.

  What he needed to do was to take the principles of the spells in the book and apply them to his own magic. He wasn't learning the spells themselves but the underlying principles.

  He squatted down, pulled out a small knife, cut open the fire lizard's chest, and took out the magic stone inside, which was only the size of a date pit.

  Magic stones were stones that grew inside monsters and contained mana. They were usually the most valuable part of a monster.

  The lizard's skin was also valuable, but Eric couldn't carry too much stuff. His goal was the octagonal fire crystal that grew below the twentieth level underground.

  He stuffed the magic stone into his pocket and kept moving forward.