The Chrono-beacon is given by Sa'at at the beginning of the Opening the Dark Portal wing of the Caverns of Time. You must complete the quest  given by Andormu outside the instance before Sa'at will give you a beacon.
- The Guardian of Time is a large bronze dragon which is summoned when you use the Chrono-beacon. When you use it, a green target will appear on the ground to determine where the Guardian will be summoned. The Guardian is useful for either cleaning up the trash creatures that come out of the portals or can successfully tank one of the elites.
- If you summon the Guardian of Time close to one of the three bosses (Chrono Lord Deja, Temporus, or Aeonus), the boss will dismiss the Guardian and the Chrono-beacon will be wasted.
- Chrono-beacon strategies
- One idea is use a beacon on wave 11 while the players rest up. When Temporus appears on wave 12, the players will be at full strength.
- Another idea for Temporus is to ignore the trash creatures and burn him down as quickly as possible. When Temporus is dead, drop a beacon on the trash mobs beating on Medivh's shield to clean up.
- Many groups choose to save 4 or 5 beacons to use on waves 13 through 17 since the time between portal openings is much shorter. Some groups even save 2 beacons to use on wave 17 so they can rest up before Aeonus in wave 18.