Fria Ligans forum

My answer might be hidden somewhere in these pages, but I'm having a hard time finding the answer. Several times, the book says that Horn's Astra need to be collected, AND the metrochrone restared before Agnostica returns. Lore is pretty clear on why the metrochrone needs to be restarted (the moon elves bound Agnostica's disappearance to the timekeeping of the metrochrone), but I can't find a lore reason for why Horn's Astra need to be collected.

My take on this is that the power of the collected Astra functions as a beacon, leading the Agnostica temple back to our world.

Also the place for it to rematerialize remains undefined until four of Horn's five sons have awoken. The awakening of the volcanoes in turn is connected to the claiming of the Astra. So the metrochrone sets the time, and the Astra sets the place for Agnostica to return.

Would be nice to have that information in the book. Otherwise the only way to summon Agnostica is by accident while chasing (and activating!) the artifacts.
Also there is no proper way to set players on the right path if they do not care about Astra.
My players are currently looking for moonstones. Lets say one of the moon elves was tasked with tying Agnostica to Aslene and decided to use active volcanos, but did not take into consideration that those could calm down in the next millennium. Then this elf's moonstone was lost for some reason and players may learn all that when they find it.