At first the player is fighting the giant puppets Old Nick and Mephista. Once they are each killed twice, the bookcase explodes to reveal Mungola. Mungola is stationary and has no melee attacks, but can cast alchemy including Fireball and Corrosion. The puppets meanwhile will continue to respawn, attacking the player as they move about. Mephista can heal Mungola, but not very much.
The fight is not very difficult, just long due to Mongola's high HP. It is more vulnerable to alchemy than physical attacks, and the presence of the puppets may make getting close difficult anyway.
The player gets 8,000 experience for the fight, and while Mungola gives no money itself, the King gives them 10,000 gold shortly after the fight.
The fight with Mungola is the best grinding spot in the game. Old Nick and Mephista will respawn endlessly, and each give 1,000 experience and 250 gold when killed, substantially more than any other enemy outside of bosses. If the player is able to defeat them simply, they may wish to consider drawing out the fight, fighting Old Nick and Mephista over and over to level up and gather money. Weakening Mungola first is advised, so when the player tires of the battle and/or runs out of healing, they can end the fight quickly.