Hope I'm right here with this, sorry if the question is too specific for this community.
Our long-term D&D campaign has reached PC level 17. Now's the time for implementing mechanics that fasten up combat (we all don't like how long it takes), as well as addressing spells that the GM (me) fears to be game-breaking (mostly 9th level spells, full list below).
Sooo... I'd be thankful for any helpful suggestions. My current ideas for the combat aspect include shock damage, Instinct and Morale checks from Worlds Without Number, but those probably don't suffice yet. And I'm having trouble conveying to the spellcasters that toning down some spells is necessary in order to maintain a functional game that doesn't tear apart hours of preparation every session. Feel free to point out any potential counter-arguments to my view on that as well.
I'm really determined to keep this game running. Thank you all so much in advance!
List of spells that require revision or more exact definition (in my opinion):
Wish, Meteor Swarm, Invulnerability, Gate, True Polymorph, Leomund's Tiny Hut, Rope Trick
We will dive into that style of play as well, yes. But there are perils left in the game world that can't be taken care of by lower-level NPC adventurers. Thanks for your feedback!