Relics are required for building upgrades, but each are specific to one specific building. Specifically, relics are used for upgrading only one building, and can only be obtained by sending those troops to collect them. Relics can only be obtained through Wilderness Raiding and Defend Cryptopia!.
TIER 2 AND ABOVE
Relics are not required for upgrading Tier 1 buildings, nor can they be collected from Forage Valley. If seeking out relics, please make sure all the prerequisites for doing so are met.
The corresponding building-type associated with each relic is as followed: