PHB
Telepathic Bond
5-level Divination
Ritual - does not require spell slot, takes 10 minutes longer
Casting Time: 1 action
Range/Area: 30 feet
Components: V, S, M
Materials: pieces of eggshell from two different kinds of creatures
Duration: 1 hour
You forge a telepathic link among up to eight willing creatures of your choice within range, psychically linking each creature to all the others for the duration. Creatures with Intelligence scores of 2 or less aren’t affected by this spell.
Until the spell ends, the targets can communicate telepathically through the bond whether or not they have a common language. The communication is possible over any distance, though it can’t extend to other planes of existence.