Advanced Sending Stones

While you touch this purple stone, you can use an action to cast the sending spell from it. The target is the bearer of any linked stone. The creature hears the message in its mind, recognises you as the sender if it knows you, and can answer in a like manner immediately. If no creature bears the target stone, you know that fact as soon as you use the stone and don't cast the spell. 

Once sending is cast through this stone, it cannot be used on the same target again until the next dawn.  

Linked stone: Any sending stone can be linked to an Advanced Sending Stone by performing a ten minute ritual. Up to ten stones can be linked to a single Advanced Sending Stone in this way.

Notes: Communication