A predatory mass of blood-sucking leeches brought together in a writhing, sentient blob by the power of a demon's soul. The Leechmonger hides in wait, submerged in a pool of scum until the player enters its midst, at which point it will burst from the foul depths and begin its attack. The Leechmonger never moves from the pit of muck that it dwells in, and instead lashes out with its two "arms" to hurl chunks of leeches at its victims.
It is possible to kill the Leechmonger from a considerable distance with a bow, but this requires that every arrow deal very high damage, as when under fire the Leechmonger will frequently regenerate health. The Lava Bow with fire arrows is generally the best choice for this strategy.
Otherwise, one will have to descend all the way down the pit while dodging the balls of leeches that the boss randomly spews around the area. If the player is hit, he/she will gradually lose HP for approximately fifteen seconds, which can be observed due to the lower body of the player being covered in leeches. At close range, the Leechmonger has few attacks, primarily relying on a horizontal double spin attack, a close-range leech ball throw (which also covers the player in leeches and gradually saps HP), and a well-telegraphed tentacle thrash attack. While the latter is difficult to dodge, it does not deal very high damage. However, it may pose a threat if the player has not been paying attention to his/her health bar while covered in leeches. While the Leechmonger does not have very high defense in general, its fire defense is extremely low. A few containers of Turpentine applied to a weapon is, for most characters, more than enough to kill the Leechmonger without much difficulty. Note that the Leechmonger can regenerate health at a fast rate. It does this by growing a ring of leeches at its middle. as long as the ring stays on, the demon will regerate health, making the fight much more difficult. The player can break the ring of leeches by hitting Leechmonger. Once the leeches are off, Leechmonger will stop it's regenerating, although it can grow another one.