The Blue Fiend was recruited by Haggar to help her capture one of the five space explorers of the Voltron Lion Force. It lives presumably on Planet Doom in a foggy, skeleton-riddled wasteland until Haggar arrives to collect it.
The Blue Fiend is large, blue-skinned insectoid with no ears, nose, or neck, pale yellow eyes, and a wide mouth containing pointy teeth with two prominent fangs. The right arm ends in a hand with five clawed fingers while the other arm is shaped like the blade of a scythe. Both arms reach below its knees. Its feet have four clawed toes, though there are also two spikes parallel backwards to the front toes. More spikes protrude from the back of its calves and between its head and each shoulder. Its entire body has red stripes reminiscent of muscle tissue. It wears a stylish white belt that appears to be made out of human bones.
Haggar and the Blue Fiend arrive on Planet Arus in the dead of night to set up their sneaky plan. Haggar's cat draws Lance to Haggar, where he is captured in a net. Luckily, Sven follows Lance and frees him, telling the Red Lion's pilot to run and get backup. Unluckily, Sven is distracted by Cova while he and Haggar are fighting, and the Blue Fiend deals him a crushing blow.
Commander Yurak uses his magnifying ray to increase the robeast's size. With Sven thoroughly injured, the Voltron Force can't form Voltron, so they attack in their lions. Bodily attacking the Blue Fiend has no effect, and the Black Lion's rockets do little more than prompt the robeast to activate its own rockets. The four lions are pushed back to the edge of a cliff over lava, where Lance gets the idea to distract the Blue Fiend so Keith, Pidge, and Hunk can safely push it - and the Red Lion - over the edge.
Weapons and Abilities
The Blue Fiend has a left arm that is literally a blade, but on its right arm is a rocket launcher. Its knees also function as rocket launchers.
- Height, weight, and weapon names taken from Voltron: From Days of Long Ago: A Thirtieth Anniversary Celebration. The book erroneously lists this particular Robeast as "Exospike Robeast", but Haggar clearly calls it "Blue Fiend" in the actual episode.