From Ars Magica
The Archmage Tower is a structure generated by the mod. The tower is guarded by 2 Tower Guardians and has an Essence Nexus at the top of it. Only one Archmage Tower exists per world and can spawn up to 2,000 blocks away from spawn. The Archmage Podium found near the top of the tower is the only way to unlock Augmented casting(And pure evil) !
10 Double chests with random spell recipes, essences, and affinity tomes
1 Brewing Stand
1 Archmage Podium