Nothing in the spell's description says the caster's allies are immune to hypnotic pattern... And if any of them are averting their eyes, they may give intelligent enemies the idea that they should look away, too....
One way to deal with cheese is to feed a dose back to the player(s). Let an enemy or two use it on them, in the same way it's being used. However, I've found the best way is to talk to the players as a group about whether anyone believes certain features of the game need to be nerfed (e.g. a gimmick spell or combo)....one particular player has learned how good it is and therefore always takes it. Always. No exceptions....
...I really hate that bit at the end when the whole party is whaling on the one poor leftover who was looking at the pretty lights while his buddies got slaughtered.
The groups I DM for always have someone with hypnotic pattern, as soon as they're high enough level to take the spell. This is because one particular player has learned how good it is and therefore always takes it. Always. No exceptions. And if that PC runs out of spell slots to cast it, they'll rest instead of fighting without it.
I was not clear: nothing in the spell's description says any of the caster's allies in the area of effect are immune. Re-reading the complaints, and looking at the range (120 feet), I see that is not a likely scenario.the defined area of affect...
at least you didn't say kill the player....Just kill the caster.
Not that many, I admit--partly because I hate running them.
Roll on wandering monster table. Oh look, a bunch of undead shamble along to disturb your rest.You're the DM. Why are you letting them do that?
I often find when GMs complain about players combat habits its because the habits are caused by how the GM runs combat. 5ft melee enemies are the worst. The are simple and uninteresting to run so the GM is just board waiting for the fight to end, but to the players there life is on the line so they are engaged and looking to find what works. If your able to make a different style more fun for you will be more likely to change things up and them in turn.