After conquering Thorvar and driving the the Legion from Arek, Danar found himself dissatisfied with his victories. He was undoubtedly the greatest force for good in the world and had driven the forces of darkness before him, but despite his best efforts evil still existed in the world. His mission to drive it out completely had stalled. Indeed, his experiments with the destruction of evil artifacts had demonstrated that evil was, in fact, a tangible, existent force that could never be completely eradicated. Thus, Danar resolved himself to a compromise: if evil could not be permanently eradicated, he would dedicate himself to containing it for all time. Thus were the Banewarrens conceived.
Below his manor house he began excavation for a series of catacombs wherein evil artifacts and items could be stored away safely. Danar laced the chambers with traps to deter those who may seek to acquire the evil artifacts and creatures trapped therein and release them back into the world. For some time his efforts seemed to be successful. The world had never seen magical wards and protective methods such as the ingenious Danar put into place. Channeling the power of divinity as well as arcane magic, it seemed possible that evil may finally be contained forever.
What happened to Danar has never been fully explained, but some have suggested that the amount of concentrated, potent evil trapped beneath his home eventually drove him to the darkness that eventually changed him into the arch-fiend Estralagos Malkith. Indeed, the malignant forces became so potent that the earth itself rejected the Banewarrens, casting them out like a pustular growth to form the Spire, an unnatural geographic mesa to the north of Thorvar city stretching all the way into the clouds. Eventually Malkith’s former companions rallied together and defeated him, but not before many of the Warrens’ banes had been released (though many of the most dangerous artifacts were even too dangerous for Danar and kept sealed away.)
The Banewarrens sat abandoned for decades after Malkith’s defeat before eventually being invaded by the Pactlords while searching for the Black Grail. With its defenses breached and the Banes once again in danger of being freed, adventurers from the Delvers Guild entered and battled against the alien creatures as well as members of House Varov (leading to the death of the current Varov leader’s sister.) This group of Delvers were detoured to the Feywild and didn’t finish the mission to seal the Warrens away, but the task was completed by another group to prevent it from being taken during the giant’s siege of Thorvar during the Elemental Invasion. With the wards finally completed, the finality of Danar’s plan came to fruition, with each of the individual Warrens scattering throughout the realm, leading to the collapse of the spire and the inadvertent breaking of the giants’ siege force and the liberation of Thorvar.