All three of these banners must be planted in the ground, with no two banners more than 40 feet apart, before they activate. An illusory mastiff manifests once all three banners are planted and walks a triangular circuit from banner to banner, moving at a speed of 30 feet. The illusory hound lasts for as long as the banners remain planted, to a maximum of 8 hours. After 8 hours, the ward ceases to function. The banners cannot be replanted and reactivated for 12 hours.
Anytime a creature of Tiny or larger size crosses into the area delineated by the banners, the mastiff erupts in earsplitting barks. At the same time, the banners summon a riding dog (as per summon nature’s ally I). The dog appears adjacent to the square in which the ward was breached; if the ward was breached in multiple areas, the dog appears adjacent to a randomly selected breached square. The dog attacks the nearest intruder immediately.
Any creatures standing within the warded area when the third banner is planted are excluded from the effects of the item, and can freely cross into and out of the area without triggering the mastiff’s attack.