Shrines can currently only be found inside Randomized Dungeons and provide the party with buffs for a limited time. These are always guarded by a lesser boss. Once the party kills the mobs guarding the shrine they will be able to activate it and get either of the two possible buffs:
The fame buff does not affect the Fame gained from Tomes of Insight.
The silver buff does not affect the Silver gained from Silver bags.
(Please add a table of the different types of shrines and exact bonuses they provide)