Thraxx is a giant insect that lives inside the head of the even larger insect skeleton in the Bugmuck. It is the first official boss of the game, and notably appears on the game's boxart.
While searching for ingredients in the Bugmuck, Strong Heart, of Fire Eyes' Village, unwittingly came across Thraxx, who captured him and trapped him in silk. When the Hero went looking for Strong Heart after learning from Fire Eyes that he had gone missing in the Bugmuck, he found Thraxx inside the insect skeleton. After an intense battle, Thraxx was destroyed, and Strong Heart was rescued.
Thraxx may appear daunting at first glance, but only the heart needs to be destroyed in order to defeat it. Thraxx casts Acid Rain and can roar, knocking both the hero and the dog back across the area and dealing damage. Maggots also spawn throughout the battle; if there are less than two maggots at any time, more will spawn until there are four. Thraxx's claws will attack the player when they get close, and can be destroyed if the player wishes.
Attacking Thraxx's ribcage will deal minor damage, and more important cause its ribcage to open, allowing the player to get inside and strike Thraxx's heart. Whenver Thraxx's heart takes damage, it retaliates with its roar attack to knock the player out of its ripcage and damage them. If the player has levelled up the Bone Crusher at least once, charged weapon attacks work well to quickly deplete Thraxx's health; use a normal attack to open the ribcage, then charge up a stronger attack once inside.
If the player is low on Petals for healing, the Maggots spawning may drop them, so the player can turn their attention to fighting the Maggots over Thraxx for a time.
Defeating Thraxx will earn 750 experience, 750 Talons, and the Spider's Claw. The player can then use the Spider Claw to free Strong Heart.