The grid of Ogham Megaliths covering Annyrion and Tartovara demarcates the web of leylines that crisscrosses the world. This network allows the Druid councils to concentrate vast energies at strategic points which they can then unleash in battle against the Wyldfolk's enemies.
Spells can be channeled through Megaliths allowing the Druids to remain at a safe distance from the thick of fight. They can also be used to store action tokens which can be leached later in the game.
Additionally, Megaliths generate a protective field around them, allowing a protection roll for troops within 5 inches.