Moth's feathers

How many grey feathers are there? I thought I had them all, but can't solve the quest. And I do have a bag of magic feathers...?

There are 38 grey feathers total. Try tapping simple walls around the same area.

Thank you!

Help!! I have 40 feathers but can’t complete the quest of moth

His quest is, "For Moth, Hall of Air Magic, Merlin's Keep, Holy Island, clean the hall of its litter of 38 grey feathers and bring him a bag of pristine, magical feathers. You might look for that bag around Castle Cymbria."

You need to bring him also the bag of pristine, magical feathers from around Castle Cymbria.

Find the Leprechaun there and he'll trade you.