"It is a window onto the greatest of all glory,
and into the deepest of all oblivion." -Askeld Urvonnus, High Priest of Nimbus

Use your Altar to Sacrifice captured Furies.

Your Priest can build an Altar. Each Altar has five runes - Sun, Wind, Rain, Thunder and Storm - which must be filled in order to complete a Sacrifice. As each rune is filled, one of the supporting bridges leaves the center and when all five are gone, the enemy Priest plunges into the abyss.

In the Campaign when you Sacrifice all the enemy Priests, the mission will usually end successfully.

In Multiplayer mode Sacrificing has a different meaning. You Sacrifice to get Knowledge from the Furies. In order to get higher level units, you must Upgrade your Altar (by Sacrificing). The Upgraded Altar (there is a level two and a level three Altar) will stay with your island from game to game. (Note that you will not be able to Upgrade an Altar that is not on your home island.) Your Altar's level must match the level of the unit you're trying to get from the Furies. Here is a table of every unit and its level.

Note that when an Altar is destroyed, a captive Priest will go free.

Click here for to learn How To Capture and Sacrifice a Priest.