Magma, a human from the Inner World, starts as a solitary wanderer before becoming a Spider Rider. Tragedy struck his early life when an Invectid raid destroyed his village and killed his family. His battle spider partner, Brutus, saved him during this attack, leading Magma to take up his Manacle and join the Spider Riders.

Driven by a promise to Brutus, Magma dedicates himself to finding Brutus's lost purple spider sister, Portia. His initial search finds no leads, but rumors later guide him to the Forest of Bewilderment. There, he briefly encounters another young Spider Rider, Hunter Steele. Despite the dangers, Magma persists in the forest, where he and Brutus defeat a spider he mistakes for Portia, Billbug.

Failing to locate Portia, Magma returns to Arachna and joins the Spider Riders, believing fighting the Invectids directly might yield clues about Portia. He assists the Spider Riders in a duel against Grasshop, solidifying his place among them. His persistence leads him to discover Portia at the Oracle's Shrine in Arachna, but she is under the control of the Invectid Big Four's Buguese, fighting alongside her rider, Aqune.

Magma supports Hunter's decision to aid Nuuma after the invasion of Arachna Castle. Confrontations with Portia and Aqune occur during the journey, resulting in their temporary freedom from Buguese's control and a brief reunion between Brutus and Portia. Buguese soon reasserts control. Magma exhibits deep distrust toward the defector Grasshop, frequently criticizing and insulting him.

During the siege of Nuuma Castle, Magma duels the Invectid general Stags but is defeated. He later confronts Buguese in the Battle Beetle Dark Opal but is swiftly overpowered. Magma witnesses Dark Opal steal the Oracle's power and attempts to reach Aqune and Portia during their forced attacks. Buguese's intervention removes Aqune's mask, permanently freeing both her and Portia from Invectid control, fulfilling Magma's longstanding promise to Brutus.

Personality-wise, Magma is passionately obsessive, particularly regarding his hatred of the Invectids and his admiration for the legendary hero Quake, often becoming tearfully emotional witnessing Quake's deeds. He also displays a laid-back demeanor and can be sarcastic or teasing, especially toward those he distrusts. His primary weapon is a morningstar, which can function as a flail.

Magma develops from a lone wanderer focused solely on his mission to a committed Spider Rider member, though he remains skeptical of former enemies. His core motivation—fulfilling his vow to Brutus—drives his actions throughout the conflict, culminating in Portia's permanent liberation.