I feel like I've been exploring the Sewers for hours already. I checked my minimap and saw my progress. All paths were explored and all that's left was a narrow passage that I didn't enter yet. There were other ways but it was blocked by bars. With only one way left to go on, I decided to enter the narrow passage.

After walking for minutes with only [Light] on my orb, everything was dark and I can only see a step in front of me. I touched the walls on my left to make sure that I'm still in the narrow passage way. Then I heard the scuttering noises in front and behind me. Multiple pairs of red eyes glowed from the darkness, staring at me.

"This is the worst! To be surrounded by rats in this tight space. [Fire Wall]! [Ice Wall]!

I casted [Fire Wall] in front of me try to scare the rats. Thanks to that the pathway brightened a little bit. I turned back and casted [Ice Wall] to block the rats from behind. The rats in front started to charge as they caught the Burning status.

"[Fire Ball]! [Charge]. [Chain Lightning]!"

I used [Fire Ball] and aimed at the floor in front of the first charging rat. In this tight space, the impact was enough to knock back the rats behind the first rat. The paralyzed sewer rats fell down so I ran forward. The [Fire Wall]'s duration expired so it went down and darkness consumed in front of me. More and more eyes glowed ahead and the sound of my [Ice Wall] breaking behind me made me panic.

"[Earth Spike] [Frost Spike]!"

The [Earth Spike] was tilted to at least obstruct the incoming rats in front followed by [Frost Spike] to slow their advance. I could only stall them and there was no way to advance or escape this situation.

But then something caught my eye on the wall because of feint light it emitted.

"[Wind Gust] [Mana Shield]! Khhh! That hurts!"

The rats that passed my [Frost Spike] was pushed back by [Wind Gust]. A rat from behind bit my leg. Its teeth didn't pierce my [Mana Shield] but if this keeps up, it will completely destroy my [Mana Shield]. I shook off the rat that kept biting me and ran towards the thing that I saw. My hand immediately touched some kind of carved pattern and at that moment, I fell in my butt as I was teleported into another area.

"Phew! That was close! Too close!"

I panted for some air and drank some MP potion to get replenish my depleted MP. As I was doing that, I looked around me and observed my surroundings.

It was a small square room with only a pedestal in front of me. There were no exit. The walls and ceiling were the same with the walls in the sewers. Only few torches were there that illuminated this room. I stood up and checked myself. There were no injuries but my some part of my clothes were tattered. My HP was reduced to 60% thanks to those rats. After drinking some HP potions, a notification window appeared.

'Congratulations! You have discovered a secret room. You can choose your rewards from the following:

1. An Empty Skillbook

2. An Equipment of your choice. Additional rewards will be given after clearing this dungeon.'

"Lucky!! I found a secret! If I didn't notice that thing I touched earlier, I would've been dead."

If a full party of prepared players were to explore this dungeon, they would be able to clear that horde of rats pretty easily. I doubt that they would notice that amidst battle. Now as for the rewards, I can still use this Novice Orb so I think I'll disregard the second option. The first option however is interesting so I chose it. A book covered intricate design then fell into my hands. I used [Appraise] on it.

'Empty Skillbook By using this item, you are able to create a skill that you want. This item will be discarded after using.'

Create a skill? Is that different from me learning new skill or spell? I did learn skills like baking and cooking from errand quests and some from understanding and imagining some spells. Well, I guess I'll just use this item first. I want a skill that can sense my surroundings. That way it'll be easier to detect my enemies.

'Empty Skillbook used.'

'You have created the skill '[Sense]'

'You have learned [Sense]'

Through observing your surroundings, the player will be able to notice irregularities depending on your current knowledge. Can also sense monsters surrounding the player.

"Oohh. This is interesting. [Sense]."

A little spark appeared from the pedestal. I touched the pedestal and a notification window appeared.

'Would you like to leave the secret room?'

"So that's how it works.  This could come in handy when I'm exploring. There's also that 'current knowledge'. I wonder if it works like appraisal. If I'm knowledgeable about things, I'll have more information then? Anyways, I have to finish my quest now so. Leave."

The view of the secret room disappeared and I was back in the dark narrow path. I can still hear the rats around me but it seemed like they haven't noticed me yet. I used [Sense] and I saw the outline of the rats. Compared to earlier, they are much lesser now. With my spells now ready and off cooldown, I casted charged until they noticed me.

"[Charge].........[Overcharge]"

After casting [Charge] for about 15 seconds, I got have 5 seconds of [Overcharge].

[Icy Mist]

[Ice Wall]

[Fire Wall]

[Chain Lightning]

I took an MP potion after using the Ice spells combo behind me and faced the rats in front of me. A slanted [Fire Wall] was erected damaging the rats that are passing through it followed by [Chain Lightning] paralyzing them for a few seconds. Two more MP potion was consumed to replenish some of my MP. A [Fire Ball] was released eliminating most of the sewer rats in front of me. [Overcharge]'s duration ran out along with the [Fire Wall] and [Ice Wall]. Some of the sewer rats behind died because of the Frost Bite stacks but the remaining survivors continued forward towards me while being slowed.

[Frost Breath]

After casting the spell behind me, I ran forward as fast as I can until I was able to exit the narrow path. The rats weren't far behind. I took an MP potion and checked the cooldown of my spells. But then the sound of a loud clang echoed the room that I came in. The narrow path that I escaped was now blocked by a gate that appeared out of nowhere. The incoming rats slowly backdown into the darkness giving me the creeps.

[Sense]

The room I just entered was a circular room with a canal of flowing waste water near the walls. It looked like an arena of some sorts which further scared me. This is a boss room, right?

When my MP was back at 100% after taking some more MP potions, I walked forward and torches lit themselves slightly illuminating the area. My [Sense] earlier detected 2 monsters. One was huge and the other one was somewhere behind it. In my minimap, the monster behind was releasing a weak glow which confused me. The huge monster in front of me started to walk towards me and sure enough, it is the boss of this dungeon.

'The Sewer Rat King Lvl.15'

The boss in front of me was readying itself on his charge, but what caught my attention was how the other monster that was hiding behind it was also moving along the canal. Before I could even understand what it was doing, the boss rushed towards me headfirst.