Seven Kingdoms: Seowyn's Crossing
Auntie Mengybone was a briar hag who haunts the western edge of the Murkendraw. She was responsible for drawing Brighthorn Castle into the swamps, causing its transformation into Blackthorn Castle. She pulled down the castle and imprisoned its ruler, the good Marquis Damarion ap Tythion in a spell to draw on his Arch Fey powers. Although it was believed that she was slain by Dame Amarantha ap Leanhaun of Idyllrise, she instead enslaved Amarantha, ruling Idyllrise through suggestion from a place hidden behind the throne.
When the Fire Wasps appeared, she decided it was time to end her latest plan. The deaths of these great heroes would give her the despair she needed to pull all of Idyllrise into the Murkendraw. In the battle that followed, however, the Fire Wasps were victorious, and the old hag was slain…one hopes for truly, this time.