On their way home, Spear, Fang, and Mira are ambushed by Egyptian-style warriors sailing in a massive warship.
This episode features the following tropes:
- Ambiguously Human: Kamau looks like a human, but he is the same size as Fang with enormous strength. The Chieftain seems to lose his humanity after he sells his soul to the Scorpion.
- Behemoth Battle: Kamau, the giant slave, fights Fang when the Egyptians capture the ship she, Spear and Mira travel on. Later, we also see him fighting a gigantic elephant.
- Big Red Devil: While its skin is black rather than red, the demonic figure that the Viking Chieftain makes a deal with is a colossal Horned Humanoid wreathed in flames.
- Commonality Connection: After being defeated and caged by the city-ship, Spear realizes Kamau is no less a captive when he sees him being led into a cage just like his own.
- Curb-Stomp Battle: Kamau offers this up to anyone who isn't Fang, and even then, he's clearly able to fight her evenly one on one. Spear and Fang once again demonstrate their dominance over most human fighters by demolishing the city defenders, making more progress for the attack than the rest of the invading army put together.
- Deal with the Devil: In the afterlife, the Viking Chieftain meets a colossal, Satanic figure that transforms him into a fire demon and sends him back to Earth so that he can avenge the deaths of his tribe and family.
- Death of a Child: One of Fang's eggs is smashed during the fight with Kamau, the partially formed fetus visible in the wreckage. It very understandably drives the three into a rage.
- Double-Meaning Title: While "The Colossaeus" is the name of the colossal ship that imprisons Spear, Fang, and Mira, the word "colossus" can also refer to —
- Kamau, the gigantic man who fights the trio.
- The Viking Chieftain, who's ultimately transformed into a hulking demonic figure.
- The gigantic Satan-like figure who transformed the Viking Chieftain in the first place.
- Fire and Brimstone Hell: The Viking chief gets dragged by a group of demonic figures into an afterlife that looks like a volcanic landscape, with the souls of the dead submerged into a lava-like substance.
- I Have Your Daughter: The leader of the city ship forces Spear, Fang and Mira to cooperate by taking Fang’s surviving eggs and threatening to smash them whenever Spear or Fang step out of line, she also does this in order to force the pair to fight in her army.
- It Can Think: Fang once again establishes her almost human level of sentience during the city siege. She watches the invaders using a battering ram on the city gates and instantly gets what's going on, and jumps in to help.
- Karma Houdini: Played straight with the people of the city-ship (the leader especially), they have succeeded in enslaving Spear, Fang and Mira and are forcing Spear and Fang to fight in their army by holding Fang’s surviving eggs hostage.
- Made a Slave: Spear, Fang and Mira are captured by the inhabitants of the city-ship, with Mira separated off with other female slaves while Spear and Fang are coerced into taking part in an invasion. Spear later infers that Kamau himself is also a slave and was highly broken by it.
- Mama Bear: Deconstructed with Fang. She's protective of her eggs to the point of hindrance, with Spear and Mira having to go through an elaborate routine just to get her to be willing to move them. Later the leader of the city-ship tries to get her to behave under threat of smashing one of the remaining eggs, but Fang either doesn't understand or is too furious over the threat to back down and would have attacked her for it, guaranteeing the loss of another egg if Spear hadn't calmed her down.
- Mass "Oh, Crap!": The vaguely Babylonian army gets one of these when Fang breaches the gate, and they realize they have to deal with a frigging T. rex.
- Mile-Long Ship: The titular warship. Despite being a wooden vessel, it looks to be about the size of a large cruise ship, houses the equivalent of a small city inside of it, and has a forest growing on its deck.
- Rerouted from Heaven: Just as it seems the dying Viking chieftain will be taken away by Valkyries, a flock of demons seize him and drag him underground to a Fire and Brimstone Hell.
- Trapped in Villainy: Fang and Spear must fight on the city-ship's behalf, or the ship's queen will smash Fang's last two eggs.
- Valkyries: A trio of Valkyries appear in the opening scene preparing to take the Chieftain off to Valhalla before he is unceremoniously Dragged Off to Hell. Instead of armored female warriors, they look like slender blonde women dressed only in loosely-wrapped sarashi-like bandages.
- War Elephants: The Babylonian-style soldiers ride on large elephants, which are different from the mammoths Spear and Fang fought back in Season 1.
