Here's where to use the Prayer Room Key you find from Fire Knight Queelign in Elden Ring Shadow of the Erdtree - and you'll need to travel to the Shadow Keep.

The Prayer Room Key is a Key Item introduced in Elden Ring: Shadow of the Erdtree. Iron key with an engraved crest. Opens the door to the prayer room in the house of worship found in the church ...

IThes 5:17 tells us, “Be unceasing in prayer (praying perseveringly).” Prayer is the master key the opens the door to victory in every area in life.