You said they take long rests if they don't have Hypnotic Pattern. Maybe you could interrupt their long rests more often - especially (but not only) when they don't have HPattern.
So the PCs have figured out how good a spell is. Has the rest of the fantasy world not figured it out too?
How does casting the spell on the players fix the problem of the player using the spell all the time?Exactly. I was thinking - EVERY spellcaster who can cast a 3rd level spell casts it on the players. Always, first. Ideally they also have the Sorcerer's metamagic for "Careful spell". As the players come up with solutions to get around it, the world reacts and starts to use the same solutions...
That said, in the game I'm a player, I'm going to ditch Telekinesis for my 10th level Sorcerer and take Hypnotic Pattern
I do not think HP is OP. A good spell yes, but not overly powerful. Here are some pointers if it is dirsupting your game: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've spread out the baddies so that they can't all be caught with one spell.
I've given the baddies magic resistance.
I've had the baddies use their turns to wake each other up.
None of them seem to prevent the fights from becoming predictable, at least where hypnotic pattern is concerned. 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.
Does anyone have suggestions for any other way to deal with the spell?
This isn't about teaching players a lesson. It's about keeping combats from becoming samey and avoiding that depressing anticlimactic mop-up phase at the end.Personally I try to avoid adversarial DMing to "teach players a lesson"
Also I think they can only do one long rest per 24-hours if I remember correctly. So if they fight a battle 15 minutes after resting and use all the hypnotic patterns, they have 24 hours before they can get another one.You said they take long rests if they don't have Hypnotic Pattern. Maybe you could interrupt their long rests more often - especially (but not only) when they don't have HPattern.