Rary's telepathic bond

Rary's telepathic bond is a divination spell that forms a telepathic link to let allies communicate. It was presumably developed by Rary.

Effect
You forge a telepathic bond among creatures, each of which must have an Intelligence score of 6 or higher. Each creature included in the link is linked to all the others. The bond can be established only among willing subjects, which therefore receive no saving throw or SR. The creatures can communicate telepathically through the bond regardless of language. No special power or influence is established as a result of the bond. Once the bond is formed, it works over any distance (although not from one plane to another).

A wish spell can make a Rary’s telepathic bond permanent, but it can bond only two people per wish.

Material Components
A piece of eggshell from two different species of creature.