Helm of Devil Command

Requires attunement
This bulky, eyeless helmet is made for a pit fiend
but magically resizes to fit. While wearing the
helm, you can see out of it as though you weren't
wearing it. You know the exact location and type
of all devils within 1,000 feet of you. You can
telepathically communicate with a devil within
range, or you can broadcast your thoughts to all
devils within range. The devils receiving your
thoughts have no means of replying to them.