Karantular

Karantular is the giant spider that Reramos used as a Trump card in the final battle against BoBoiBoy.

Background
Karantular was a beast that resided in Planet Windara. Kuputeri imprisoned it in the basement of Kupuri Palace using her Wind Elemental Power to stop it from breaking havoc. At one point when Kuputeri was healing herself in the cocoon from the aftermath of Retak'ka's battle, Reramos used LampBot to control the ancient spider to be used as a last resort in moment of emergency.

The Battle for Windara!
When BoBoiBoy and his friends defeated the Five Generals, Reramos unleashed Karantular to defeat them. He used his webs to trap the team. BoBoiBoy uses his elemental split to split into BoBoiBoy Thunderstorm, Ice and Cyclone and freed himself from the webs. BoBoiBoy Cyclone freed Kuputeri from Reramos's chains while Thunderstorm and Ice attacked the Spider. Karantular soon defeated Thunderstorm. While Ice was fighting, Kuputeri told Cyclone that the only way to defeat Reramos is to use Tempest Power. When Karantular defeated Ice, instead of attacking Karantular, Cyclone attacked Reramos and tried to take LampBot from him. Reramos lost LampBot and as a result Karantular was freed from its control. This proves to a bad news as Karantular went berserk and completely out of control. Cyclone trapped Karantular in his Cyclone and tried to push him away from the castle but failed to control its winds. Atlast, Cyclone evolved into BoBoiBoy Tempest and defeated Karantular with one attack.