Relaxing stones

When 3 or 4 relaxing stones are linked and
activated within 9m of eachother, they create a perimeter with a relaxing atmosphere. The
activator of the stones is not affected by the stones.
It takes 1 hour to link the stones and 1 minute to activate or deactivate the stones.
Creatures within the perimeter have to make an intelligence check (DC16) each round. If they fail,
then they will have difficulty concentrating (spellcasting mod -3) and their speed is halved.