Nivdriv

Their travel set, they began their long journey toward the mountains.
The roads themselves were fairly peaceful. Bandits aren't really much a thing outside the outskirts. Monsters don't hang around those parts either. An entire week sounds like a painful travel time.
Fortunately, Jeff knows how to make it entertaining. Borghild's pretty fun too. In his own way.

Jeff: "So Borghild. Tell me some more about you."

Borghild appears fairly old, even for a dwarf. His beard almost completely white except for few blackened hair left, his skin makes him look younger than the actually is. 

Borghild: "About me? What would you want to know from an old man?"
Jeff: "I don't know. What do you like?"
Borghild: "Beer and women."

Jeffrey chokes on his own saliva, laughing.
Yeah. This is going to be an interesting travel.

Jeff: "How'd you learn magic? I thought dwarves weren't capable of using magic at all."
Saito: "They can't?"
Jeff: "No of course not. Where do you come from?"
Saito: "Not from Glarion that's for sure."

Borghild gives him the side eye.
Borghild: "I'm not allowed to tell anyone."
Jeffrey: "But they've exiled you."
Borghild: "I have my honour." 
Jeffrey: "Alright then. Keep your secrets."

The elder nods.
Borghild: "Can you use magic?"
Jeff: "No, I can't."
Borghild: "Why not?"
Jeff: "What do you mean why not? I just can't."
Borghild: "I'm sure there's a reason."
Jeff: "I don't know?? Because of my bloodline maybe?"
Borghild: "Fine then. Keep your secrets."

His face goes wide. 
This is funny. He could spend his days listening to them ragebaitting each other.

Saito: "Say Borghild. Tell me more about that dragon."
Borghild: "It's name is Nivdriv. She's an ancient dragon that has condemned the dwarves to the mountain since the dawn of time. Whenever they'd try expending out, she would attack, killing every dwarves in the way, destroying every structure. The mountain is her territory, so she doesn't want us on it, forcing us to live underground. Her breath is a literal beam of ice. As you probably figured, she's a snow dragon. In my fight against her, I'm torn a couple scales off its chest, but that's the most I could do.
Saito: "Are their scales as hard as hard as the legends says?"
Borghild: "Undeniably."

That sounds difficult. An ancient dragon is probably absolutely massive. Punching this thing and blowing it up probably won't make a dent. He'll probably have to use his sword and aim where the scales fell off. Then boom! Blow up the dragon from its insides.

Saito: "Okay, I've got an idea of how to go at it."
Jeff: "That sounds like you."

Borghild: "Oh? I can't wait to see that."
Saito: "Just wait."

The first couple days of travel were kind of just fun and peaceful. However, reaching the fifth day, they are now at the feet of the mountains. The mountain range goes as far as the naked eye can see. The temperature is starting to drop around here. Snow begins to softly fall from the sky.
Luckily, they've bought warm clothes as they were heading north, anticipating this weather. 
With a quick break, they'd gear up, now going onward. The day went without issues. At most, occasional monsters appearing, trying to get the jump on them. Saito just kicks them away, sending them flying. They're not worth their time.

The sixth day is where the mountains truly kicked in with winter storms.
Visibility becomes horrible. It's hard to see further than three lengths of your own arm.
Borghild takes the role of the guild, showing them the way.
Luckily for them, despite minimal clues on where to go and how to guide themselves, Borghild seems to know exactly where to go, even with his eyes closed. Whenever they needed to rest, the dwarf would create an ice dome, completely sealing them from the outside world, allowing them to rest and breathe without having so much snow go down their lungs.

A dome now over their heads, Jeff collapses down, exhausted.
Jeff: "How much further is the dragon? I can't in this cold.."
Borghild: "Don't worry. The storm should normally go away soon. The sky is clear. Nivdriv probably was nearby."
Saito: "Should we be ready for battle?"
Borghild: -She won't bother fighting three lone travelers. But the moment we get close enough to her lair, yes, she will engage us without warning.
Jeff: "Saito... How are you handling this weather?"

The hero tilts his head, thinking. He is level 71. The more he levels up, the more he seems to grow resistant to conditions such as these. But even before then, back where he lived, the winters would grow very cold while the summers could kill you from dehydration. Maybe he simply has a resistance to it.

Saito: "I'm used to it I think. My homeworld had much snow during winters. Drink water and take your time."
Jeff: "Right.."

After a respite, the group went outward. Like Borghild predicted, the storm soon came to an halt, allowing them to travel the rest of the day without difficulties.

On the final day, a roar alerted them they were getting near their goal. The mountains would shake, a powerful wind would occasionally build up. 

Borghild: "We're near."

Yeah, I can tell.
By making themselves small, they were able to get closer, remaining undetected.
Now near the top of the mountain, a cavern can easily be noticed at the distance. The entrance itself is massive, with gigantic ice spikes protruding from many different places and angles.
Over the centuries, the constant departure and returns of Nivdiv have flattened the ground leading to the cavern. A perfect battleground.

Borghild: "I didn't ask. But you're confident you can take a dragon on, yes?"
Saito: "Yeah. I'm stronger than any champion there is in Glarion."
Jeff: "I've always wondered why you never challenged the Kingdom's hero to a duel."
Saito: "Why would I do that?"
Jeff: "If you win, you take their place"

That's a thing?? NOBODY EVER TOLD ME THAT.
Saito: "What would that give me?"

Borghild gives the protagonist an annoyed look.
"Can this wait after we've killed this dragon?"

Both of them apologies.

Borghild: "I see it sleeping in its lair. If we can sneak up on it, we could do something."

While he's right, this isn't how Saito imagined himself taking on a dragon. 
It's just.. It's not everyday you get to fight one, you know? This is something he was looking forward to.
Saito: "If you allow me Borghild.. I'd like to do this my own way."
Borghild: "You're the boss. You said you'd do it. Whether you succeed or fail is on you regardless.

Cool! He can genuinely fight the dragon in a cool battle.
A large smile on his face, Saito goes running, buffing his body, dashing forward.

Borghild: "Is he usually like that?"
Jeff: "No. He's normally serious and efficient. I think he really just wants to fight the dragon."
Borghild groans. Underestimating a dragon wouldn't do you good.

Half-way through the lair, Saito stops himself, activating a second spell.
A large ball of exploding mana appears in his hand.
With insane speed, he releases it at the roof of the cavern. 
It takes roughly four seconds for the orb to reach its destination, striking the roof of a colossal sound. It's the equivalent of a bomb going off. A giant explosion occurs, melting part of the snow and ice everywhere on a fairly big radius. The dragon roars, forced awake, as the explosion burns it from above, the cavern collapsing on top of it. The roaring of the dragon rapidly gets muffled by the explosion and the cavern falling down, covering the dragon, trapping it within its own home.

Saito: "Come out and fight me!"

This is exciting. 
It's such a powerful contrast. Two years ago, he was fighting for his life everyday, not knowing if he'd live to see the next sunrise. He felt overwhelmed by almost every powerful foe he encountered. But now? He's at the top of the food chain. He's grown to enjoy these moments. 

With the strength of a titan, the dragon breaks through the mountain's rocks, furious. Its eyes are spinning around with uncontrollable rage, finally locking onto Saito, standing still in the middle of his lair.

The dragon opens its mouth, releasing its breath. A beam of ice lashes onward, creating spikes of ice that grow from the floor, splitting the very ground in half. The entire floor freezes immediately, ice overtaking everything the beams comes in contact with.

(Can I take this or do I dodge?)
Never worth the risk. Being too cocky can be a man's downfall.
"Side step."

Activating an active skill of his, Saito almost nearly teleport sideways, avoiding the beam with ease.
In a raging fit, the dragon flies up. Like an eagle to a pray, it flies down with the speed of a racing car at max speed, swooping down at him, claws extended.

Borghild: "PILLARS"
Casting a spell of his own, giant pillars suddenly burst half-way between them from the ground, rising up the sky of an incredible speed. The dragon collides with the ice of a solid impact, staggering it. 

Coating himself of red mana, Saito leans forward, about to leap.
"Lion form. Berserk. Forward."

His buffs allowing to become much stronger, he leaps very high up the sky, perhaps 4 floors up, reaching the dragon. It leans down, attempting to bite at his aggressor.
"Release!".

Opening his palm forth, Saito casts yet another spell. The mana in his hand builds up with incredible density, turning from red to a bright burning crimson, releasing an explosion even more powerful than the first. The sound produced from such effect sends ripples through the mountains, creating several avalanches at once. Borghild's hands quickly rushes to his ears, screaming.

Borghild: "AAAHH. THIS WILL GET ME DEAF"
Jeff: "WHAT?"

The impact is so powerful that the dragon loses control and fails to maintain himself into the air, coming down crashing into the floor with a great bang.
Saito drops to the floor, landing on his own, uninjured. This kind of fall isn't enough to hurt him anymore if he has enhancements on.

The protagonist's eyes rapidly look at the dragon's body, looking for the missing scales.
Despite all these massive explosions, the cavern collapsing, the dragon crashing against the ice and hitting the floor from that fly up, it doesn't look injured at all. He must destroy it from within.
Nivdiv stands back up and roars, its throat lighting up of a bright white. Its about to unleash yet another one of its breaths. However, as he thinks about dodging, his eyes suddenly lock onto the dragon's lower stomach. There's few scales missing.
(THERE!)

Using several of his skills and spells. Saito comes bursting in, barely avoiding the beam and a giant ice spike growing right beneath him. As he closes the distance, he unsheathes his sword, reaching for the dragon's weakness, lunging forward with all his might. The moment the sword pierces through its body, the dragon screams in agony.

(Screaming already? You've seen nothing yet."
"IMPACT!"
The inside of the dragon blows up. A shock-wave goes off and smoke immediately rises from the dragon's mouth. It tries to struggle, it tries to roar, to move. But it's too late. The insides have been destroyed.

Saito leaps back to avoiding the collapsing body falling onto the floor with a massive thump.
Nivdiv has been defeated.