Yharnam, Pthumerian Queen
Yharnam is the final boss of any Pthumeru Ihyll Chalice Dungeon.
The Queen isn't too tough to take down, but you have to be cautious. The main rule of the fight is this: attack once or twice, then back off as you hear the baby cry. Otherwise, you'll be caught in a binding spell, completely open to attack. When it comes to the Queen's attacks, she'll begin with area-of-effect and ranged blood blasts, both of which can cause rapid poison damage. Sidestep up to her, deal damage, and back off. Once she breaks her handcuffs and starts using dagger swipes and charges, be ready to dodge a little quicker.
Your strategy should change once she starts moving more. If she spawns clones (which she will do frequently), take them out first. They go down in one blow, but use all the same attacks. You also need to watch for when she starts channeling into her dagger. She may either cause a row of blood spikes to chase you or multiple burst from the ground. In either case, keep moving and keep your distance from her. Finally, watch for any large glowing ring around her, and get out quickly if you spot it - it's a pretty big energy attack.