The Icon Below
In a previous age a great evil was defeated and its minions banished to other planes. The evil and its greatest lieutenants were to powerful to be removed from this plane completely so they were sealed within the world’s core guarded by magical wards.
Over the recent ages the wards created by the Archmage are acting like giant magnets pulling at these prisons. A symptom of this phenomenon are the living dungeons. At the moment they provide adventure and riches. How long will it be before they cough up something so foul the current icons are forced into action?
In the ages after the banishment previous icons sought to remove any memory of this age from history in the hope no evil tries to quicken the end of all ages and summon the forgotten evil from the forgotten age.