I'm not a Goblin Slayer

[Magic Missile Proficiency +1]

Level 1 Spell: Magic Missile Lv.1 (4/10)

"So tired..."

Casting the spell had succeeded, but it still drained him.

Not as badly as last time when it had completely wiped out his mana—but still enough to leave him mentally fatigued.

If failing to cast the spell a few times brought his fatigue level to a 1, then successfully casting it was like a 5.

He lay down to rest.

After about half an hour, the foggy exhaustion in his mind finally faded.

His 7 Intelligence was doing its job.

His mental recovery speed was simply beyond what normal people could manage. For most, that kind of mental drain would've required a full night's sleep. He just needed a short nap in the sun.

His mana, too, was recovering little by little every day. Slowly, yes—but steadily.

Watching it grow day by day gave him confidence.

Unfortunately, even with his current mana pool, casting Magic Missile was still expensive.

He'd only awakened to magic a week ago. He needed more time to fully digest the benefits of his enhanced Intelligence.

"Is there a way to lower the mana cost of Magic Missile?"

Since he couldn't expand his mana pool quickly, Gauss turned to saving instead of generating more.

To be honest, the spell's current power output felt like overkill.

Take goblins, for example—he didn't even need full power to kill them. Even that big hobgoblin could've been taken down with maybe 30–50% of the spell's full force.

And ordinary goblins? Probably 10% of the spell's current output would've been enough.

Of course, that was just a gut feeling—he had no hard data.

Still... worth testing, right?

Even if he couldn't throttle it down to 10%, being able to cast at 80% or 90% would help reduce mana burn, allowing more frequent casting and faster training cycles.

Because right now?

His training intervals were way too long.

After resting a bit longer, his mana slowly regenerated.

Gauss took a deep breath and tried again.

This time, he didn't rush into the full casting sequence.

He stopped right when his mana began to flow.

Sounds simple, but interrupting a spell mid-process was much harder than it sounded.

Once the magic started channeling, it had a sort of momentum. Stopping that flow required precision and strong control.

Fortunately, his high Intelligence helped—he managed to halt the spell on the first try.

Now came the hard part: fine-tuning.

To simplify it: casting a spell was like executing a pre-written program. Once you hit "run," the system took over. Most mages only needed to trigger the casting process, and the rest was automatic.

The hard part was building the "program" in the first place—a detailed spell model in the mind.

But this also had a downside: relying too much on this "black box" meant the caster couldn't customize or control the spell's inner workings.

"I want to intercept and hold back part of the mana at the start of the cast."

If he could cancel a spell mid-cast, why not control how much mana went into it?

The tricky part was how much to intercept—and doing it without breaking the spell.

And so began a long series of:

Fail. Rest. Try again. Reset. Try again.

By the time the sunset dyed the grasslands orange, he had finally managed to cap Magic Missile's power output at 95%.

That meant he could shave off 5% of its mana cost.

Doesn't sound like much—but it was huge progress.

He had started at 1%. Now, after hours of focused practice, he had inched it up.

It was proof that his method worked.

He was on the right path.

Stomach grumbling, Gauss packed his things and headed back toward town.

…

Five sunrises and sunsets passed.

Each day, he trained hard.

Morning till night.

Casting. Resting. Recovering. Repeating.

His hard work paid off.

Magic Missile Lv.2 (1/20)

Not only had the spell leveled up, but his mana pool had expanded significantly.

If his original mana capacity had been 1 unit, he now had 1.5 units—a 50% increase.

Granted, these were just his own rough measurements—no official metric existed. But the difference was clear enough to feel.

He had also improved his mana control.

He could now cast Magic Missile at 60% power, which he nicknamed "0.6-unit missiles."

At his current level, that meant he could cast two 0.6-unit missiles and still have 0.3 units of mana left.

The lower he pushed the spell's power, the harder it became.

After all, Magic Missile required a certain baseline of mana to function.

It was like trying to run a car on less and less fuel—you could optimize it to a point, but it still needed a minimum to keep the engine running.

"Alright, that's enough for now."

Training was done—for the moment.

Gauss exhaled, letting the tension drain from his shoulders.

These five days had flown by—but they had been intense.

Mental strain. Mana depletion. Repeat.

What was supposed to be a break after the Birchwood mission had turned into even more exhaustion.

He laughed quietly to himself.

Still, it was worth it.

All that training meant something. In a future crisis, every drop of sweat spilled now would pay off.

He was no longer helpless.

He now had solid combat ability.

Even at 60% power, Magic Missile could easily kill a hobgoblin—and he could cast it twice.

If he had been this strong that night in Birchwood, the fight would've gone very differently.

With a reliable trump card in hand, he finally felt some relief.

Ever since arriving in this world, he had felt a constant sense of urgency, a pressure that kept pushing him forward.

That urgency was why he kept chasing after every scrap of power—magic, swords, survival tactics.

Now, he had Magic Missile.

And with it, a real sense of security.

Among low-tier adventurers, few could match his raw firepower—even without a formal class.

Now that he had a baseline…

Gauss's hands were getting itchy.

Time to find a few goblins.

Test the results of his training.