Overlord Volume 04

The Lizard Man Heroes is the 4th light novel volume in the Overlord series, released on July 31, 2013.

Summary
Having a need for stronger bodies so that they can create stronger undead Ainz orders that the Lizardmen will be annihilated to create stronger undead and thus strengthen Nazarick.

Detailed Summary (Spoilers) 

The story begins with Zaryusu Shasha waking up and then thinking about the lizardmen current situation. They are in a really bad spot, there used to be seven tribes but because of food shortage a war between the tribes started which eventually led to the seven tribes becoming five. They also had to make laws about food gathering to make sure that the surviving tribes had enough food to live on. Still the lizardmen believe that the strongest should rule and survive and see's this occurrence as a natural thing in life. This morning however is interrupted when an undead magic chanter appears and declares that within a few days their undead army will appear and kill all the lizardmen.

Zaryusu Shasha quickly volunteers to inform the other tribes in hope that they can face this enemy together. He leaves together with his pet and friend Rororo that is a four headed hydra. He first arrives at the Red Eyed tribe and there meets with Crusch Lulu who is their leading figure. The two of them quickly fall in love with each other and together they travel to the next tribe who is led by Zenberu Gugu. In order to follow Zaryusu wants to have a duel with him since he is the bearer of Frost Pain one of the four treasures of the lizardmen. After Zaryusu wins, Zenberu together with his tribe joins them and time is advanced to the day of battle.

Cocytus is the one who has been sent from Nazarick to destroy the lizardmen and at his disposal he has been given five thousand undead as well as an undead magic chanter named Iguvua=41 created by Ainz himself. He has however been ordered to lead this army from the back giving out orders but he himself may not appear on the battlefield. Believing that his army which is more then twice the size of the lizardmen will easily win, he simply orders them to attack head on. To his shock however the lizardmen turns out to be much stronger then he thought and it is clear to see that they are winning against the undead horde and in a last attempt to win sends out Iguvua=14. After a fierce battle between the leaders of the lizardmen together with Rororo against Iguvua, the undead horde is defeated. Cocytus surprised at his defeat and shamed at losing an undead created by Ainz has no other choice but to return to Nazarick, he is however deeply impressed by the lizardmen.

Upon his return he is scolded for his failure and is given the order to annihilate the lizardmen with a stronger army. However Cocytus asks if they could spare the lizardmen instead and make them as part of Nazarick. Ainz is happy at this development since he wanted the guardians to experience a real army battle and was also impressed with the lizardmen and he also wants them to join Nazarick. So he changes his order from annihilation to occupation and that as Cocytus punishment for his failure is to be given control and responsibility over the lizardmen once they have submitted to Nazarick.

The day after the battle the lizardmen see's a new undead army has appeared surprised at how quickly a new army could be assembled and doubly so when they see the composition of the new army. While the undead army again seems to be composed of five thousands undead this army is completely different compared to the other army. The previous army had broken and rusty weapons and armor they were also very disorderly. This undead horde on the other hand is fully equipped with magical weapons and armor, not only that, each and every item seems to be a unique and powerful magic weapon. While one of the big kingdoms might be able to field an army fully equipped with magic weapon they would at most have weapons that were mass produced with a simple enchantment they could never deploy an army with such diverse enchantments and with each soldier seemingly holding a powerful weapon. If that was not enough the leader of this army cast only one spell and instantly froze the entire wetland into ice.

Seeing as the undead leader wants to parlay Zaryusu and his brother Shah Sue Liu Shasha goes forth knowing that they have no chance to win against this enemy. They are then told by Ainz that he is impressed with their previous battle and has decided that he will instead of destroying them, make them submit to him instead. He also informs them that he previously only sent one of his servants Cocytus to do battle against them but that he was told not to fight himself. They are then given the condition that if they can defeat Cocytus in battle, Ainz will no longer bother them however if they lose or decide not to fight they must submit to him. Zaryusu before leaving decides to ask Ainz why he froze the lake area to which he responds that he didn't want to get mud on his shoe's. Zaryusu then truly realizes that Ainz must be a powerful demon and they have no chance to win against him seeing as he would use such powerful magic that they could not even dream of using for such a reason.

With a heavy heart Zaryusu and Shasha returns to the lizardmen and informs them of what they have been told and seen. Knowing that they have no chance to win but still deciding that they must at least challenge this Cocytus, they pick out the fifty most elite warriors among the lizardmen and then goes to fight against him. Cocytus by just activating his passive area of effect makes all but five of the elite lizardmen unable to move among the one's able to fight are Zaryusu, Zenberu and Shasha. They are however no match for Cocytus and everyone is killed by his hands. Lulu having been told not to join the battle and to stay behind to lead the lizardmen kneels before Ainz and submits to him fearing that they will now be treated as slaves. Ainz instead responds that they will be treated fairly as subjects under his rule and that he will leave Cocytus to lead them.

Zaryusu wakes up surprised to be alive as he knows that he was previously killed by Cocytus. He finds Ainz standing there with a magic item that has brought him back to life and the lizardmen kneeling around him revering him as if he was a god. The lizardmen having no god to pray to and only honoring their ancestors. Zaryusu quickly realizes that someone with power like Ainz can't be a magic chanter or a demon, he must be a real god. As these thoughts circles around in his mind he collapses exhausted from being brought back to life.

Chapters

 * Prologue
 * Chapter 1: Departure
 * Chapter 2: Gathering, Lizardman
 * Intermission
 * Chapter 3: Army of Death
 * Chapter 4: The Dawn of Despair
 * Chapter 5: The Freezing God
 * Epilogue
 * Volume 4 Special Edition

Trivia
Web Novel
 * Main story remains quite the same. Just some 'daily life' parts of Nazarick are added in the Light Novel version.