As an invading Dark Spirit. Her invasion can be triggered by walking out to the right from the second bonfire in the poison swamp.
- Black Phantoms will only spawn if the player is in human form and the area boss has not been defeated. This means that defeating a boss before being invaded by a particular NPC Black Phantom will forever deny that Black Phantom from appearing in that area on the current playthrough.
All her attacks are pretty slow due to the size of her weapon and can be easily dodged. So wait for her to charge up her attacks, get behind her and do as much damage as possible.
She staggers pretty easily with the right weapon. With enough stamina, one could end this fight fast.
Be wary of moving into the poison and of mosquitoes moving in to attack.
Sometimes Mildred can be stuck right after the fog gate in Quelaag's boss room and will roll around doing absolutely nothing useful for the remainder of the boss fight.