Inside Two Rivers is the eleventh episode of At Azmuth's College.
Ben is showing the class Upchuck, because Azmuth is teaching chemistry, specifically the transformation of matter. Then Sektor gets in the separate classroom and yells Albedo is on Earth and tries to achieve immortality.
Evfnye and Sektor call Vektor and go to Earth. They land in Mesopotamia, where an alien contact occurred in 4700 BCE.
Ben uses Goop to search for Albedo, and he finds him as Humungousaur, who achieved the Immortal star. He throws Goop in the Tigris river and goes ultimate. He shows his new allies, the Celestial Bull and Khubaba. They are revealed to be alien monsters. Ben uses Echo Echo to fight them, but Ultimate Humungousaur destroys the clones. He also injures Sektor's legs, and Vektor brings him back home. Evfnye tricks Ultimate Humungousaur to launch the Celestiall Bull far away, to Euphratis while Khubaba is distracted. Evfnye sends a message to Niklas so he sends his snakes to Mesopotamia. They defeat Khubaba, but Ultimate Humungousaur fights Ben, who improviously goes Spidermonkey and shoots a web so that Albedo can't see anymore. Niklas' snakes throw him into the river, and Evfnye is disappointed, because Albedo did steal the Immortal star.
- Sektor gets injured.
- Albedo steals the Immortal Star.
- Celestial Bull