An excerpt from To Slay a Dragon, by EN Publishing
As the party goes about collecting the items that will eventually slay her, Cirothe isn’t just sitting on her hoard waiting to die. Though she is quite removed from most events, she does have a network of kobold cultists that are involved in some minor way in every story-relevant encounter (and in some random encounters), and she knows, in a broad way, the activities that go on in the lands just outside the Desolation.
As a way of harassing the PC party, Cirothe launches from her redoubt every few days to terrorize the populace. As the stakes rise and the party gathers more items (and gets more total stars), her attacks become more brutal, eventually wiping entire towns off the map completely in an effort to stamp out the runts who dare give those cowering mortals hope.
The chance that this happens is represented by the Dragon Dice, which should be a single d20. This d20 is rolled every day, and on a result of 20 or greater, Cirothe flies out from Skull Mountain and wreaks some havoc in the world. As the party gathers stars, the group should add the total number of stars the party has to the result of the d20 roll (from +1 with one star, to +12 if they have all the stars).
When Cirothe destroys a location, it is replaced with ruins and filled with kobolds. Refugees flood into neighboring towns (if they’re intact), though some stay and try to rebuild (and fight against the kobolds who move in). Cirothe destroys about half the people in a given town, so if the DM would like to determine if a specific NPC is alive, simply roll 1d20, and on an 11 or better, they are. The DM can also pick and choose certain NPCs to live or die, depending on their needs for the rest of the adventure.
If you roll a location that Cirothe has already destroyed, then Cirothe instead sends kobold cultists to destroy the party (as if a 20 was rolled).