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Who would win?

A huge *****ing dragon that eats actual darkness.

One misty spell.
One pestilent boi
Midir is just like any other boss. Fight em enough and you learn their patterns.
I killed him with:
Black Bow of Pharis +10
Feather Arrows and Fire Arrows
Hawk Ring
Chloranthy Ring+3
Life Ring
Estus Ring
Ember Activated
Fire resistant gear, but with medium weight equipment.
40 str/40 dex
Just keep your distance, roll when he charges for you and run away, stay out of his fire, laser beams and spooky heads and shoot shoot shoot!
Would a +10 Sharp Crow quills buffed by a +10 Yorshka's chime with lightning blade and 40 Dex plus hunter's ring and Leo ring good enough to crush this guy to oblivion?
Lol I don't think you want to trade for the leo rings effect
he's practically already dead
tfw when Midir catches you in his mouth, bakes you like a potato, then spits you about 300 feet, but you survive with like 10 HP and somehow survive the rest of the fight on NG+7... i've never felt so damn lucky in my damn life, especially considering I was NOT wearing very good armor. a good, proper dragon fight is all I've ever wanted, and From finally gets it down to a T.
if youre having problem managing stamina try using dragonslayer spear and poke 1 or 2 hit everytime he finish his combo, and dont forget to learn his attack pattern.
I just noticed that when you knock Midir off the bridge, he doesn't fall into a dark, bottomless pit that eventually leads to the underground chasm we fight him in, but he's actually falling into the black swamp. I found this out when I was tooling around the half-submerged building guarded by multiple Ringed Knights, and noticed that the black swamp extends all the way up to the base of the cliffs that the Church of Filianore is seated. In fact, if you look carefully from the bridge itself, you can see the slightest hint of watery texture in the pit.

Doesn't seem important at first, but this also means that we, too, managed to pass this barrier of black water without knowing and somehow ended up in the chasm. Most people associate this black water with the Abyss, which makes perfect sense, but I wonder if it could instead be a representation of the Deep that Aldrich was obsessed with? After all, it says in the trivia here that the water in Midir's arena is filled with the same ruddy body parts as in Aldrich's arena. Even more concerning is the fact that Aldrich's habit of cannibalism lines up well with the Locusts' obsession with the feast (and yes, Gael's consumption of the Dark Soul, but for the sake of argument...).

Last but not least, there are pools of this same black fluid in the Dreg Heap that spawn forth the Murkmen, and if you get a good look at them, they're all covered in barnacles. In the description for the Soul of Aldrich, it says that Aldrich had envisioned the coming of the Age of the Deep Sea, suggesting the Deep does, in fact, have something to do with a body of water. The Deep is also associated with Human Dregs, which the Murkmen drop/cast/transform into, and the Dregs are also said to be the "shackles that bind this world," acting as a sort of foundation for existence.

Or, maybe the black swamp thing was just a total oversight on From's part, and I'm talking***** out of my mouth.
*****ing bad designed boss camera is a nightmares and gets you killed oneshot laser aoes and he turn way to quickly u lose tracking very often and on top of that all high immunitys and just to big healthpool did anyone at fromsoftware beta test at all this *****ing boss and didnt noticed that flaw ?
you might just be bad
A wise man once said - gid gud
Yeah, the optional boss that they wanted to make the hardest in the game has too much HP and resistance and his attacks are too OP.

Git gud
he is in bowsers wee\dding
Its just mind blowing what side should i choose, remark the guy for not being able to kill midir or the "GIT GUD" ppl. In both catagory you are all autistic. The git gud chuck norris is a type of cancer that spreads for no reason. it has no cure (Bec its ledgit 99% of the community). We all get it that you are gods and perfect but does it really matter? does anyone care in this day and age? while the guy complaining about the boss, you ledgit dont need to lock on the boss. Just patience and persistence and you might just get the hang of it. (Ironic as it sounds that im talking to strangers but i just like to hate and remark and criticise ppl bec its fun.)
My favourite strategy to use is to run as far away from the boss door as possible and go have a cry in greirats cell.

In all seriousness, I find midir to be one of the toughest most rage inducing bosses I have fought in a long time, he beats my buttocks every time with those damn hard to dodge attacks, on top of that when he charges I have the hardest dodging or spacing myself enough to get a beat on his head... And I *****ing love his fight, it is tough, it is brutal it is damn rewarding when you finally beat him. Hadn't looked too deep into the lore but what I've read so far it goes deep. My tactic for when I finally beat him, run around like a headless chicken and pray to RNGesus that he doesn't flick you away
Pestilent mist isn’t good against him he is constantly moving so it doesn’t hit him very often
Its amazing against him you just need to time it dummy
Stay under him hitting his ankle until he rears back to breath beneath him. Run to his tail and cast mist on his foot and start hitting his tail with R1s.

When he turns around sprint to his head for running R1 then run to his feet and tail again.