The easiest way to damage Aldrich is by hitting his tentacle tail, so you’ll want to stay behind him. After a while, Aldrich will slam his halberd into the ground, creating a dark vortex around him. Stay away from the vortex, but continue hitting his tail if you can. When Aldrich disappears into the vortex, he will appear again on the opposite end of the room, so start running there to prevent him from using the dangerous spear attack.
Once you’ve gotten him down to half health, Aldrich’s halberd gains fire damage and he’ll start using some fire attacks as well. However, his attack patterns will remain the same; you just have to be more wary of the fire on the ground. It doesn’t do that much damage, but the damage you take from other smaller attacks can add up and stunlock you to death. One thing to be wary of is his moonlight arrow attack. The arrows will follow you around for much longer than they did in the first phase, and getting caught in them will usually spell instant death. Make sure the arrows go away, before you continue the assault.
Aldrich is one of the more annoying bosses in Dark Souls III, especially if you’re impatient, but his moves can be easily read and dodged. Take your time with this fight, and he’ll be done in no time,
Be sure to check out our Dark Souls III wiki for more tips and tricks.