To destroy the nest of bugs, we need to catch their leader first.
Xilunker is the largest tree goblin in the swamp, and I believe the queen of the Brain-Infesting Maggots lives inside the goblin.
Because of the queen bug's presence, Xilunker is tremendously powerful. You must defeat it - kill it and drive out the queen bee. He lurks in the forest to the south of the fortress.
Xilunker was originally a tree goblin in a particularly tall tree.
When the water quality of the marsh deteriorated, Xilunker went through some, shall we say, changes. Cylice pointed at Xilunker.