Slithraa is the second-in-command of the Hypnobrai tribe. The former general, after being accidentally put under the control of Lloyd Garmadon and leading his tribe into Lloyd's battles, the general is challenged, ultimately defeated, and replaced by his second-in-command, Skales.
After the Hypnobrai ice caverns were discovered by Lloyd Garmadon, Slithraa approached the boy and attempted to hypnotize him, but the general was hypnotized into Lloyd's command after his own power was reflected on an ice shard.
After this, Slithraa ordered the tribe to attack Jaimonikai Village to steal sweets for Lloyd, resulting the ninja's intervention and loss of the staff. However, Skales manages to hypnotize one of the ninja during the battle. Following the defeat, Skales questions this new "childish agenda", but the general ignores his second-in-command and continues to obey Lloyd's orders for ultimate bad boyhood.
Soon thereafter, he orders the army to begin construction of a treehouse, and Skales reveals to Rattla that he hypnotized and sees what one of the ninja sees, and that Slithraa is completely unaware of it. An angered Slithraa then orders the two to stop slacking off and assist in the construction. Despite Skales' second objection on the new missions, he is once again dismissed. After the ninja's attack on the treehouse, Skales traps Lloyd in a wooden-barred cage and travels to the the Ninja Monastery to retrieve the staff. After returning to the ice caverns, Slithraa demands his staff from Skales, who refuses. The tribe demands a face off in the Slither Pit, in which Skales defeats Slithraa. Skales claims the staff and grows a tail, becoming the new general. Slithraa's tail disappears, and he pledges loyalty to his new superior.
When he was the general, Slithraa's entire body was blue with goldish yellow markings, possibly signifying his rank. After being defeated by Skales, his tail disappeared and he grew legs, and he had less markings on his body and his arms turned gray. Instead of holding the Hypnobrai Staff, he now uses a sword in combat.
"You dare challenge my command?!" -To Skales, who claims right to the staff
"Give up your mind. I will control you." -During a failed attempt to hypnotize Lloyd
"You know better than to question my judgement, Skales. I'll pretend you didn't ask." -To Skales at the treehouse