From 832 IE to 834 IE, a series of monster plagues roamed Valorim and wreaked havoc, throwing the continent into disarray and forcing Empress Prazac I to declare a quarantine. However, a band of adventurers employed by the Kingdom of Avernum's Unspecified Services were able to defeat the monster plagues and bring peace to Valorim.
The plagues were created by the Vahnatai in retaliation for the Empire's theft of three Crystal Souls several years earlier. The plagues were slimes, cockroaches, troglodytes, giants, golems, and alien beasts.
Main article: Slimes
The slimes were arguably the least threatening of the Plagues. They possessed little intelligence or strength. Basic metal armor was able to resist their slime for a moderate period of time. Although deadly against an unprepared human, they were little more than fodder against a city guard or watchful citizen.
The bandit-mage Jordan performed experiments on the slimes. He found that the slimes rose up out of crude pools of ooze which could only be destroyed by fire. He stole some of this ooze and used it to create his own slimes. These slimes served him and his brigand allies, moving with their raiding parties while Krizsan Province was in chaos.
Dubious reports tell of other experiments being conducted in the Slime Pit itself, apparently by the slimes themselves without any supervision. These supposedly included attempts to merge with other living beings and to hold solid shapes.
Using fire, which the slime pools were quite sensitive to, the Surface Explorers were able to cleanse the Slime Pit and kill the Alien Slime, a gigantic, semi-sentient creature that appeared to act as a central hive-mind for the creatures.
Main article: Cockroaches
The cockroaches originated in the Filth Factory, a massive building housed in the mountains north of Shayder. Each roach was at least the size of a large dog. Despite this, they were easily dispatched in battle. The problem they posed was the ease with which they passed on parasites and diseases.
The Anama Church, which had spread throughout the Isle of Bigail and was centered in Shayder, was well-suited to deal with disease; their prayers were dedicated to cleansing the world of pain and sickness. However, there were too few priests; each worked efficiently, but simply too many people contracted diseases and required curing.
The Empire's local representatives were powerless, because the Anama had assumed control of Bigail in all but name, and feared to lose this control if the Empire took an interest in the province again. Between the boycotting efforts of the church, the relative isolation of the island and the presence of other, more immediate threats on the mainland, the local government could not hope for reinforcements. They were forced to seek assistance elsewhere, and received it from the Surface Explorers.
Main article: Troglodytes
Having been created for this single purpose, the troglodyte society was entirely built for battle. Most of them were proficient warriors, and some were powerful spell-casters. The troglodyte people were ruled jointly by a warrior and a shaman. A council of distinguished veterans also handled lesser affairs and advised the top administrators.
The troglodytes boldly raided many cities and caravans, leading to several settlements being eventually abandoned because of the danger. Although some troglodytes farmed, most simply lived off the spoils of their campaigns.
Their threat was eventually ended by opening the barrier separating them from their ancient enemy, the giants. The resulting war between the troglodytes and the giants prevented both of them from attacking human settlements again.
Main article: Giants
The giants lived in a series of caves close to the home of the troglodytes, but the two were separated by a mountain chain. The center of giant territory was in Karnold Province, but they mainly raided the Midori Province. Their favored weapon were thrown rocks. They were about twice as tall as a human, and extremely muscular.
Giants lived in tribes which feuded for more space and power. Some tribes separated themselves depending on which deity they worshiped. However, there was also a religion which most of the giants worshiped; a massive temple was dedicated to the gods of this religion within the giant caverns.
Giants were not known for their intelligence. A few mastered clerical magic became shamans. Such shamans were able to cast spells from far away. Most, however, used physical weapons, like clubs and thrown rocks.
By engaging them in a war with their enemy, the troglodytes, the giant threat was effectively eliminated.
Main article: Golems
Rentar-Ihrno modified the standard model of golems to create animated stone which was specifically designed for attacking, not defense. Golems swiftly moved through the dense forests of Monroe Province, destroying all living things in their path, human or not.
The golems were a lethal force. Some soldiers used Skribbane, a powerful and addictive drug, to temporarily heighten their senses and make them more skilled in combat. In the cities, which were in constant danger of being attacked, the same drug was used by some civilians to escape their fears.
General Baziron led the fight against the golems in the northern reaches of Monroe Province, but the administration of the province did not approve of his tactical style. Faced with a foe incapable of fear or pain, Baziron realized the need for stealth and guerilla tactics, abandoning the Empire's tradition of frontal attacks with overwhelming force.
The source of the golems, also named the Tower of Shifting Floors was eventually raided and destroyed by the Surface Explorers. The golems were left without guidance and were quickly swept away.
Main article: Alien beasts
The alien beasts were the most terrifying of the Plagues. They were dark gray monstrosities with six legs, enabling them to run at extremely high speeds. They also posessed powerful neck and jaw muscles, capable of ripping limbs off bodies.
Alien beasts are highly-mutated canines. They cannot reproduce naturally; instead, pups are grown and raised in magically-maintained vats of fluid.