Dark Souls 3 - Darkeater Midir, SL1 No Damage

Some people consider Midir the hardest boss in the game (or even the series), but it's really not that bad after you learn it a bit. It significantly more manageable (and fun) once you work out you're better off staying in front of him and not locking-on. It's easier to see what he's doing and his head takes significantly more damage and can later gives you an option for a crit that destroys a tonne of his HP.
Whilst a lot of his attacks can seem quite flaily, they're all pretty well telegraphed and you can dodge the majority just by taking your time and dodging away from him. For his first attack where he flails whilst breathing fire and crawling towards you, you can just chill out near where you land and he'll usually end-up right by you for an ez charged headshot. One attack to watch out for is his charge because the telegraph is deceptively subtle and the actual damage frames come out quickly; the key is to look at him slightly relax by pulling back a bit. Once you see the telegraph, the dodge timing is pretty generous.
He takes meme damage if you attack his body, so aim for his head at all times. He has a chunky amount of downtime between his attacks and tends to lower his head to the same spot, so take advantage by charging up your heavy attack when you can.
His second phase is more annoying because he's much more aggressive, so getting hits in between attacks is much tougher. I was probably more cautious than I needed to be here which makes the fight drag on, but if you take your time, you'll always get an opportunity to bonk him. His most notable new attack is the huge laser barrage, but it has a specific pattern if you want to learn it. Otherwise, I find just running / rolling diagonally tends to work or just cutting the distance. He also has the attack where he dives with one claw, roars and then a bunch of humanity spirits come out of the ground. You can easily dodge this by running to the side, though just watch out if he does any follow-ups.
I definitely recommend the Dragonslayer Axe for this fight, it has great damage at Lv1 anyway, but the innate lightning damage is good against Midir. Pair it with lightning resin / bundles for even better damage. I didn't have RTSR equipped for some reason, but at SL1 basically everything Midir does will 1-shot so you may as well (the damage buff is slightly higher than Lloyd's).