Sanctum of Tranquil Light
Legendary Enchantment — Shrine
: Tap target creature. This ability costs 
less to activate for each Shrine you control.
An untroubled mind Dwells in perfect harmony With a peaceful heart.
Johannes Voss
Core Set 2021 (M21)
• #33Rulings
Each Shrine has an ability that counts the number of Shrines you control. These abilities include the Shrine they're printed on.
(wotc • 2020-06-23)
The cost reduction applies only to generic mana in the cost of the activated ability. It can't reduce the {W} requirement.
(wotc • 2020-06-23)
Shrines count only enchantments with the subtype Shrine. Other cards with “shrine” in their name (such as Jungle Shrine, Luxa River Shrine, and Nantuko Shrine) don't count.
(wotc • 2020-06-23)
Rulings
Each Shrine has an ability that counts the number of Shrines you control. These abilities include the Shrine they're printed on.
(wotc • 2020-06-23)
The cost reduction applies only to generic mana in the cost of the activated ability. It can't reduce the {W} requirement.
(wotc • 2020-06-23)
Shrines count only enchantments with the subtype Shrine. Other cards with “shrine” in their name (such as Jungle Shrine, Luxa River Shrine, and Nantuko Shrine) don't count.
(wotc • 2020-06-23)