CODE VEIN

I have read this is the hardest battle. It is, if you fight close combat. I found out that range is super easy. A suggestion from what I used.
Companion: yakumo (deals high damage and keeps the boss close to him)
Blood code: Artemis
Weapon 1 hanemukuro (or whatever)
Weapon 2 brodiaea or whatever bayonet that shoots long range (you get this from gifting Mia)
Blood veil: night claw
Gifts whatever suits you. Only passive I used is bayonet mastery. And on the right spot you will need "restorative offering" to revive your companion.
Now on the shortcut items you need regeneration and ichor concertate.
The way to easy win is keep him at long range and shoot with the bayonet with y button. Try to dodge all the time. With bayonet it's easy to dodge.
Easy win, dodge and shoot.

In this video guide I will show you how to defeat Juzo Mido in the Crypt Spire. This will probably be the hardest fight of the game for most people. So I would highly recommend using Blood Guard, Cleansing Light, Fouldblood Barrier, and Hasten. With these you can negate his blood spells, heal back damage, get a free hit on you, and maneuver better.

A few things to note. If he hits you with his blood spells you will lose all your buffs and you will not be able to use your abilities. Same goes for your partner. So be careful and mindful when being hit by this because it also means you can't revive your partner and same goes for them. One other thing, I noticed using Yakumo was a better choice than other partners for the shear damage. So beating Juzo quickly is key.

For starters Juzo has some pretty powerful swings and reach. He has combo moves up to three hits. He will mix in his sword with a melee swing from time to time. He will dash at you with the same melee hand as well. He will also cast a few different blood spells at you, one will home in on you. Make sure they don't hit you if you can help it. Once he is about halfway he will extend is sword and cast a spell. There will be two balls orbiting around you. Once you see them get closer together you will see them collide at the end point. Before they do and explode, you will need to dodge out of the way. At this stage when he swings at you from the distance he will be shooting projectiles at you with numerous swings. He will have a charge lunge attack also, it's a slow build up. Make sure to get some distance once you see it start to happen. The rest of the fight will be him repeating these moves. Once he is defeated the achievement will pop.