Zeratul's beacon is a protoss structure used to teleport Zeratul onto the battlefield. In an alternate timeline where Zeratul survives the opening stages of the End War, the dark prelate used this device to deploy himself onto the field.
Zeratul's beacon is the structure Zeratul spawns and respawns from in Co-op Missions. When Zeratul falls in battle, he will return to the beacon. His initial spawn takes 240 seconds, while any susequent respawns will take 60 seconds.
Protoss Units and Structures of StarCraft II
Versus units and structures
units and structures