I will (possibly) be DMing "Hoard of the Dragon Queen", a 5e adventure which was designed for 4 players starting at level 1. I will be needing to scale the adventure to account for more players (6) and higher levels (at least level 7).
My players have a lot of experience when it comes to keeping themselves safe when resting, but the latest additions include a Wizard with the "Leomund's Tiny Hut" spell as a ritual. I have no problem with the use of the Tiny Hut, and I, as a DM and a palyer, love the idea of being able to lay down for a full rest without worrying about being harassed.
Sometimes, though, as a DM I would like to be able expose the party's complacency by simply having a creature that has a built in ability to cast "Dispel Magic" on the Hut. I don't anticipate using this creature as a minion of a larger force to get them killed – a large attacking force would have a scout that would advise such force to wait the party out or approach stealthily, or any number of other ways of dealing with it.
The creature I want doesn't necessarily have to be one that would attack the party on site, just one that would be a nuisance. If it is one that would attack the party, it shouldn't be one that is too difficult for them to deal with given their level and makeup (mostly ranged attackers/ranged casters).
The setting for HotDQ is the Forgotten Realms (in which my previous experience is limited to older video games like "Icewind Dale") but things native to that setting are preferential.
I know that as DM, I have the prerogative to give any creature that can cast magic spells the "Dispel Magic" spell, but I am more interested in creatures that start off with it and have been balanced as having it "out of the box".