Abyss Watchers is the first Lord of Cinder you will face in Dark Souls 3. The music is fantasticly sad and will set a slow apathetic mood to the fight. But, don’t let that fool you, the fight is anything but slow… To begin the fight the Abyss Watcher will come at you swinging. It’s best to dodge through his attacks and try and pull off a back stab if you can or hit him a couple of times, before backing off and repeating. You can also parry him if you prefer. Keep your shield up and if you have a good fire shield, I highly recommend it for this fight. At about half health a second Abyss Watcher will spawn. I recommend backing away from both of them and simply blocking and rolling as you put distance between you and them. The reason being, that a 3rd abyss watcher will spawn shortly after and will begin to attack them. Once this happens it’s your cue to jump back in. It doesn’t really matter which abyss watcher you hit, as killing the decoy takes nearly the same length as the boss, so I recommend hitting whichever is closer or easier.
Be wary of the 3rd watcher, as even though he is attackign them, his hits can still damage you. Once the Abyss Watcher is down a cutscene will play and he will get up off the ground and be seriously pissed off. He will be more aggressive and his weapon will be coated in fire (this is where the fire shield comes in handy). There will be no help for you this time so you’ll just have to git gud. In this phase you’ll want to doge more left or right than usual.
The boss now has a tendancy to leave fire trails after the attacks and if you roll directly forward or backward you will most likely be hit by these, even after you dodged the initial attack. The boss doesn’t have a whole lot of health, so if you made it through the first phase well enough you should be ok for this part. Wait for his jump attacks and dodge, then hit him in the back a couple of times if you are having a hard time finding an opening. .
As found on Youtube