The Dominion is the name of the empire established by the druins who were led by Vespian from their world into this one, after he carved a portal using the sword Vellichor. The druins ruled over and enslaved both humans and monsters. Vespian became the Archon, the ruler, but he lost his peoples’ trust when he began killing other druins to try to reincarnate his wife, Astra. A rebellion led to the downfall of the Old Dominion, and the druins became recluses and outcasts. Lastleaf wants to create a New Dominion after he defeats the last remnants of the Republic’s army, which is under siege in Castia.

A druin is like a human but taller, stronger, and more graceful and athletic. Druins have magical abilities and long, rabbit-like ears. In this realm, druins typically live for hundreds of years, though they can be die or be killed. In the contemporary world, druins are now rare and generally live as outcasts or travelers, like Shadow.

After the fall of the Dominion came a short-lived Empire, but the first Emperor proved to be a tyrant, and his people rebelled again. The Emperor’s son fled through the Heartwyld Forest and over the mountains to establish the Republic of Castia, located in the area known as Endland. This is the Republic that Lastleaf gathered the Horde to fight; he wants to replace the Republic, which is why he calls himself the Duke of Endland. After the Battle of Castia, when the city is repaired, the citizens create an Empire and make Matrick their Emperor.

The owlbear becomes a running joke in the novel because everyone believes it is a mythical creature, now extinct. Moog, however, believes they exist and wants to see one, which is one indication of his childlike innocence. Moog proves correct when the band discover that owlbears do exist in the mountains, but they have to kill the adult they see when it charges them. It turns out the owlbear was protecting its two young cubs, which Moog then takes charge of.

The Heartwyld is a vast forest that lies between the area of Grandual, which is now divided into five kingdoms, and Endland, the lands to the west of the mountains called the Emperor’s Mantle. The Heartwyld is full of creatures that range from the magical to the monstrous, including trolls and the tribes called the Ferals. The Heartwyld is where one might catch the rot, the wasting disease also known as the Heathen’s Touch. The warriors that make up the Horde are mostly summoned from the Heartwyld.

An ettin is a creature with the body of a man, though typically larger in size than the average man, and which has two heads. Ettins are not generally dangerous unless they are threatened. The ettin that Saga encounters has two personalities, Gregor and Dane. Dane is blind, and his facial features are disfigured, but his personality is sweet and sunny thanks to the way that his brother, Gregor, describes the world to him. The ettin serves as an example that creatures thought to be monstrous may not be threats, highlighting The Blurred Line Between Human and Monster.

Ferals are the tribes who live inside the Heartwyld. They live by hunting and are known to eat whatever meat they can find, including that of humans and each other. Jeremy, a Feral whom Saga encounters in the Heartwyld, is a member of the Boneface tribe. The tribe is ruled by a chieftain, who is served by Jeremy’s father, Teresa. It is a custom among the Ferals to take on the name of the first person they kill, which is how Jeremy’s father acquired his name.