Early on in my current campaign my players were sent on a quest by a wizard friend of theirs, he gave them a sending stone so he could keep in contact with them. After that quest ended my players got a nice big downtime, 1 month. One of my players, who owns a tavern, asked to dedicate that downtime to finding some more sending stones, one for each player and the pairs to be held by the barkeep NPC she employs. I rolled on the tables in XGtE and got a price that they could afford.
Are there any unforeseen downsides in letting them spend all their money on sending stones? I know this effectively gives them party wide telekinesis but since they’re using this NPC as a telephone switchboard (literally how they pitched the idea) I can reserve the right to say he’s busy and can’t forward their messages.
I decided to give them the stones and then ran a session, they got separated for a few minutes and spent most of it talking through that npc to each other instead of trying to solve the problem that separated them. They’ve implemented a rule that he needs to write down what they say and relay the message exactly. 10/10 it was quite funny. Try doing this with your players.
The most obvious thing to do is have the NPC be replaced with a doppleganger minion of your next big bad so that the sending stones end up passing along disinfo (splitting the party, giving wrong directions, getting them to discard a magic item under the false belief it is cursed, etc)
This would be good if they received a surprise gift of stones, but is pretty awful for the players who took the time to find the stones intentionally.
You’re not wrong, however, they can have their toys back after they figure out what happened and rescue the NPC. It’s a good hook and requires them to think about spending some of their treasure to shore up their home defenses. For all we know, their players are murder hobos and this is well deserved comeuppance.
My players aren’t murder hobos, but the tavern is in a bad part of town and suddenly has a bunch of magic items