The Lizard Man Heroes Arc
- Main article: The Lizard Man Heroes Arc
Cocytus was ordered by his master Ainz Ooal Gown to take charge of leading the undead army of Nazarick and used them to wipe out the lizardmen located in the Great Lake. Seeing that his own army was about to be defeated by the lizardmen, Cocytus began to seek out a request from Demiurge. Left with no other choice, he deploys his trump card, the sub-commander Iguva=41, onto the battlefield. When Iguva=41 got killed off by Zaryusu Shasha and the Lizardmen Alliance had triumphed over his undead army, Cocytus accepted his defeat and that his mission to annihilate the lizardmen was a total failure on his part.
The undead army consisted of a total of 4950 undead monsters, not including the commander and their retinue.
The army is composed as following:
- In the Web Novel, the Army of Death was estimated to be bigger in numbers as it consisted of 5720 undead monsters. Among that amount, there were 2500 zombies, 2500 skeletons, 400 Undead Beasts, 200 Skeleton Archers and 120 Skeleton Riders.