And if you want to exploit the Bowhole for easy leveling up to 45 or so:
Go to the platform with the stairs leading to the boss room on the third floor then touch the bottom left, top right and bottom right corners of the platform and wait there. Enemies will continually spawn and then walk offscreen to despawn. Just wait for a Liquid Metal Slime to appear, rush it down and kill it for about 10,000 XP on each of your party members. Repeat as desired.