Bathcat

Bathcat is an NPC that can be found in The Goldmines, Delvemore Dungeon, and the Halls of Din. She can be fought to enter Delvemore Dungeon before defeating Selt. She is always accompanied by Toadvine, who really dislikes her.

She cannot be fought to unlock Lillyth as she will just teleport you and lock you out.

Fighting Bathcat
Bathcat acts very similar to a Priest, except she can create a shield that negates all damage. If you keep attacking her, she will not be able to create the shield.

She can heal Toadvine, so taking her out first can make the fight easier. There is an Oil barrel right next to her. Note that getting stuck in Oil will slow you down and disable jumping, making it easier for Toadvine to attack you.

Bathcat barely does any damage. If you have a lot of health, you can simply just keep hitting her until she dies, and tank the damage.

She can be set on fire and hurt by Bombs. Since they will not attack until you attack them, you can start the fight by planting a Bomb next to them to start the fight at an advantage.

Fighting with Bathcat
You can have Bathcat and Toadvine as allies in Halls of Din 4, in front of the gate before defeating Noori. By talking to them you start a fight of 3 waves of Scale Tunnels. Keeping Bathcat alive is recommended due to her quick healing, which can help the player greatly.