Warlock, known as War-Rock in the original Japanese, is an FM-ian alien from Planet FM who arrives on Earth after betraying his kind. He holds critical knowledge about the disappearance of Subaru Hoshikawa's father, Kelvin Stelar, forming the initial basis for his partnership with Subaru. They merge through "Denpa Henkan" (EM Wave Change) to become the EM Wave Human Rockman, combating threats within the EM Wave World.

War-Rock exhibits a gruff, pragmatic personality contrasting Subaru's initial timidity. This dynamic evolves during battles against FM-ians pursuing the Andromeda Key, a planetary annihilation weapon War-Rock stole. His motivations shift from self-preservation towards protecting Earth, especially after the FM-ians revive Andromeda. During this crisis, War-Rock's connection to Subaru deepens, culminating in their use of "Star Force" to sustain Andromeda and destroy the key, saving Earth.

In the Tribe storyline, War-Rock accidentally ingests the Sword of Berserk, an OOPArt from the ancient Mu civilization, during a museum conflict. This grants Rockman the Thunder Berserk transformation but causes War-Rock significant physical strain and exhaustion. The OOPArt's sentience is revealed when the "tribe of Berserk" tries to sever Subaru's consciousness and possess his body to revive Mu. War-Rock fights to maintain control, demonstrating his commitment to protecting Subaru at great personal cost.

War-Rock's development intensifies during the pursuit of the remaining OOPArts (Dinosaur and Shinobi) alongside antagonists Hyde, Gori Monjirō, and Burai. He confronts Doctor Orihime's betrayal, as she orchestrated the search to resurrect the Mu entity Le Mu. When Hyde extracts the OOPArts from War-Rock, he terminates the EM Wave Change to shield Subaru, leading to his capture. Later, reunited with Subaru in Mu, War-Rock supports Rockman's transformation into Tribe King to combat Le Mu. His arc concludes observing Earth's restored peace beside Subaru, subtly acknowledging their bond by showing Subaru former adversaries coexisting peacefully.

Physical limitations recur, particularly when using the Berserk form's power exacerbates War-Rock's fatigue. This vulnerability is starkly highlighted during battles against Burai, where exhaustion leaves them defenseless. The fusion's psychological aspects surface when the Berserk tribe exploits their weakened state, forcing War-Rock and Subaru to confront their interdependence to overcome external possession.

War-Rock's background as a warrior from Planet FM remains consistent. His relationship with Subaru transitions from utilitarian to genuinely protective. His role expands in the Tribe narrative as the OOPArts' power tests his resilience, cementing his evolution from fugitive alien to guardian committed to Earth's safety.