Source: Bestiary 3, pg(s). 59
A crossroads guardian is a being created by the fundamental primal forces of the world to complete dangerous tasks and quests when no other option seems available.
Crossroads guardians are not necessarily restricted to one form, though they typically appear as humanoids. They are also not fundamentally restricted to a certain suite of abilities, with, for example, some being more martially focused and others being more diplomatic. Rather, each crossroads guardian arises in the form best suited to fulfill the need that brought it into existence. Vitally, a crossroads guardian need not be working for a goodly cause, but rather any cause that drives nature to action.
While specifics can vary greatly, all crossroads guardians are united by a few common powers and restrictions. Crossroads guardians have an innate understanding of who they are speaking with, and can always greet that individual in their own language. This allows the crossroads guardian to know who may best aid them in their quest. When the crossroads guardian finds a suitable hero who is willing to serve, they can place a geas on that creature to guide them along the quest and even travel with them.
If the target of the crossroads guardian's need is an object to defend or use, the guardian must remain within 100 feet of that object. Else, the crossroads guardian is similarly restricted to the place of its summoning. If a hero accepts the crossroads guardian's geas, however, the crossroads guardian can freely follow and aid that hero on the quest.
Finally, no method of destroying a crossroads guardian before their task is complete is known. Each time such an effort has been attempted (typically maliciously), the crossroads guardian has reformed at the site of their original summons within a day. The only known way to remove (or release) a crossroads guardian is to enable its quest to be completed, at which point the crossroads guardian may adopt a new quest elsewhere or simply dissipate back into the primal magic of the world.