In 855 IE Rentar-Ihrno exacted her vengence on Avernum by sending the sea monsters and the Shades. It was a rough time for Avernum as trade routes were blocked, cities destroyed, and panic-stricken people wondering when it would end. The 'war' only lasted some 8 months before the Shade Killers came to the rescue. It took them 4 months, but they defeated the shades, got rid of the sea monsters, and killed Rentar-Ihrno.
Sea Monsters and Shades
The Sea Monsters inhabited the watery areas of the caves of Exile. They completely brought an end to sea-to-shore trade by destroying the trading vessels. They were created by an immensely powerful lich named Anastasia who took up residence at Khoth's old lair. The Sea Monsters eventually died out when Anastasia was killed due to lack of care.
The Shades, however, inhabited 5 of Avernum's biggest cities (Formello, Silvar, Almaria, Blosk, and Dharmon). They caused massive hysteria and paranoia. City dwellers absolutely would not deal with outsiders when the shade was in the town. This was esspecially difficult for Almaria because its shade never left. Blosk also took a heavy hit and was nearly totally destroyed when the soldiers there attacked the shade. Which in turn made Dharmon protect the shade to keep the same fate from their town.