Buguese acts as Mantid's second-in-command and leads the Invectid Big Four, driven by deep resentment toward the Spirit Oracle for depriving sunlight from his people. This fuels his desire to retaliate against her perceived injustices. Typically angry and ill-tempered, he maintains a strong-willed, commanding presence regardless of circumstances. He claims minimal concern for comrades but demonstrates respect for Stags and protective concern for Aqune, whom he mentors. He shows underlying care for Beerain, though he often disregards her feelings, and prioritizes ending his people's suffering above all. Visually, he has pale skin, long white hair tied in a ponytail, and green eyes partially obscured by a mask, dressed in a black tunic and burgundy cape.

Originally loyal to Mantid, he gradually loses faith and secretly plots to overthrow him, aiming to obtain the Oracle Keys to restore sunlight to Invectid lands and seize control of the nation. To execute this, he feigns unwavering loyalty while manipulating events, including deploying the mind-controlled Aqune and her spider Portia as weapons against the Spider Riders. His discovery of Aqune in the Forest of Bewilderment led to her upbringing under his guidance, utilizing a control mask to direct her actions.

During the Nuuma campaign, he loses control of Aqune and Portia after their liberation by the Oracle. After recapturing them, he orchestrates the siege of Nuuma Castle, using Aqune to retrieve an Oracle Key before abandoning allies to their presumed demise. Later, he negotiates with the Spider Riders for an audience with Mantid, contingent on their delivery of the Oracle Keys. This agreement collapses, leading to a duel with Hunter. When an injured Beerain attempts to expose Mantid's treachery, he publicly dismisses her to avoid Mantid's spies, though he later regrets this action.

Mantid's gift of the Dark Opal machine backfires when it drains power from Hunter's Oracle Keys, confirming Mantid's betrayal and Beerain's warnings. In response, he removes Aqune's control mask, acknowledging her importance to him and granting her freedom despite anticipating lethal reprisal from Mantid. Beerain and Stags rescue him from near-fatal injuries sustained during this confrontation. In the final battle against Mantid, he allies with Beerain and Stags to protect the Spider Riders, delivering his two Oracle Keys to Hunter. He witnesses the restoration of sunlight to the Invectid lands, expressing relief at their renewed future.

His relationship with Mantid evolves from years of devotion to attempted rebellion after recognizing Mantid's self-serving motives. His dynamic with Aqune blends control, protectiveness, and reluctant respect for her pacifism, culminating in her voluntary liberation. Interactions with Beerain involve ignored affection and subsequent regret over his harshness, while Stags earns his unspoken respect. He treats Grasshop with consistent cruelty and dismissiveness, demoting him from the Big Four, though he eventually saves him from Mantid. Hunter initially incites his hatred as a symbol of the Spider Riders, but their clashes foster mutual understanding, leading to trust in delivering the Oracle Keys.