My Upgrades are Invincible. Rewrite

Even hiding dozens of meters underground and controlling the Sword Array, the fight continued as the last two healthy heads of the Amphisbaena raged violently as the dungeon-born monster knew it was doing its creator-given duty in killing as many adventurers and people as it could.

With more than half its heads actually crippled I could tell through my connection with the Sword Array that although the Amphisbaena had more intelligence then the usual dungeon monsters. It had alreadly accepted its death, it wasn't trying to blow up spells with its elemental breath.

It was just trying to kill literally everyone it could sense.

But something happened a couple of minutes later... As another another powerful volley of spells under the direction of Riveria slammed into the Amphisbaena. 

The fucking spells knocked the cursed bolt of blindness from the monster's body.

And a roar of elation rang out from the Amphisbaena as its sight was restored to its primary still surviving two heads. With the crystalline head falling limp to the ground.

I grumbled a cursed as I knew I needed to get out of here as the Sword Array worked via having the flying swords coming back to the array every minute or two to have their mana stores refilled and the connection strengthened.

Getting out of my buried state just had me throwing all the previous stuff I piled onto myself back into my inventory with my brain ringing as I could feel the overuse of my mana hitting me hard at this point. 

I was but a fucking humble level two, I shoudn't have been involved with a level eight god damn enhanced floor boss.

"Mages, retreat! The last head on the right is immune to magic!" I heard Riveria yell out in panic as the magically immune headshot a blast of pure magical energy towards where a bunch of mages were presumably at.

I heard a yell of anger from a male voice and then from the wrecked remains of Melen I saw Gareth, Loki's famous dwarf warrior running towards the Amphisbaena. But he was rewarded for his daring charge with the Amphisbaena viciously spinning with its long draconic tail whipping like a tree thrown in a tornado at Gareth.

Gareth swung his mighty war axe upon the massive tail beaming towards him... And in slow motion, I saw his axe bite into the flesh of its massive tail that was bigger than Gareth's whole body.

And then the axe stopped, and the tail didn't stop with Gareth being smashed and ran over into the ground via the tail of the Amphisbaena.

'Still a level eight monster... A level four or whatever Gareth is at this point isn't going to be able to do real physical harm to it.' I thought as I flexed my mana to force the largest Greatsword in my sword array to slam into the throat of the Amphisbaena's magically immune head and then I realized something.

If that head was completely magically immune... It would make fucking sense why the Amphisbaena kept attacking me even if I had stuck it with the blindness bolt, it could only see with that one particular head actually.

But for now, it didn't know I was still alive from its previous attack, so as I watched as Finn of the Loki Familia and other melee adventurers tried to move into take out the magically immune head so that the mages could finish off the last head to truly kill the monster...

I had an evil idea.

See, I was realizing the scales of the Amphisbaena's were just too damned hard, and it had alreadly learned with me taking out two of its heads personally that it needed to keep its scaled eyes squinted lest I shove more swords into its eyes.

There was just one thing though... Monsters were anatomically correct.

Once they left the dungeon and their monster stone fused into their bodies, they were perfectly capable of breeding, and living a 'normal' life of a monster.

Sooo with the Amphisbaena covered in thick as-hell scales and our mages being either fucking obliterated by the magic-spewing head or fleeing the battle as they were out of mana... I decided to go for the nuclear option.

'Fuse.' I thought as I fused the broken remains of the swords that made up the first iteration of the sword array into a thick, fluted drill bit.

Integrating the drill into the Sword Array, my mind once again pulsed in pain as I was running out of mana as I controlled the foot-long drill bit to fly around the Amphisbaena and then with my mental connection with the drill bit... I found my target.

The Amphisbaena screamed, no it howled it unbearable agony, both physically, mentally, and spiritually as the drill bit. Did as its name implied and drill through the scaleless, defenseless hole of its anus and shot itself into the Amphisbaena's guts.

'I will not ever explain how I did this.' I thought with shame as I controlled my other flying swords in unison as the Amphisbaena's heads stretched as far as they could upwards with their mouths open and eyes gaping wide in an indescribable expression of soul-deep agony.

And all my other swords slammed home into the two remaining heads four eyes. With the Amphisbaena being unable to react beyond a violent shudder that broke one of the fucking greatswords with its eyelids snapping shut with the force of its eye lids closing.

But that was just one sword destroyed, and there were at least three other swords in each eye that mulched said eyes and began the process of trying to break through the eye socket to enter the Amphisbaena's brains for each head.

Meanwhile, the drill bit was shooting like a deranged high-speed barbed bullet as it bounced off the seemingly unbreakable ribs and other bones as it tore through defenseless much softer organs.

But finally... The drill bit hit paydirt. With a mighty cracking noise, even from within the Amphisbaena, I heard the drill bit hit the dungeon monster's monster stone with the drill cracking it open and shattering it.

The Amphisbaena gave a weak snarl as its heads turned towards me with hate in the expression of its bleeding eye sockets before it slumped and quickly broke down into motes of energy as it died via its monster stone being destroyed.