After defeating Midir, meet Shira in order to receive Titanite Slab.if you want to keep your distance, use ranged lightning attacks.When you do enough damage he will stagger and allows you to finish him.As he gets low HP he goes berserk and can knock you off the safe spot so evade during his tantrum and get in the final few hits.Avoid it by taking distance and coming back to attack his arms, wrist and head. When you are close to him, he claws you with 2-3 hit combo. When he looks downwards he sprays fire on the ground near him then it fans out and follows with a dark laser beam.

Try to get behind him and look for a little safe spot he mostly can't hit you in.

When fighting Midir on the bridge: It can be best to charge him down before he fully stands up and attacks.

Video Example of location from the Shared Grave Bonfire. Knocking Midir off this bridge will not reward the player any souls, it is simply a pre-requisite that unlocks the boss fight. Simply drain his health and knock him off the side of the cliff and he will be waiting for you in his boss room. There will be another bonfire and Midir will be waiting for you on the other side of it.

You will need to cross the bridge that Midir torches continuously and make your way up the ruined stairwell (past the Moaning Knight).

Then simply drop down the hole behind the altar.Down the ladder is the shrine room where the Shira summon is.Break the illusory wall and head down the path.Look for the statue not holding a sword, it is an illusion.Head left at the junction into a circular room filled with statues. Using the lift, Halfway down there is an opening, jump/roll in.Darkeater Midir is found in The Ringed City: After opening the final shortcut gate near the Ringed Inner Wall bonfire.Midir, descendant of the Archdragons, was raised by the gods, and owing to his immortality was given a duty to eternally battle the dark, a duty that he would never forget, even after the gods perished. Darkeater Midir is a Boss in Dark Souls 3, available with the The Ringed City DLC.

Dark souls 3 midir