I'm A Banana
Potassium-Rich
This I agree with, but I think there is room for change without it suddenly being "not D&D."
Save or suck spells as afflictions would be a food way to go. Your initial save result determines where you start on the track. Follow up failures make it worse ultimatelyending in REAL BAD, while follow up successes lessen the effect until CURED.
Like Flesh to Stone. One of the things I'm fond of in 5e's sabateur design is that they do use a diversity of approaches.
But, really, the trouble here is that you want your encounters to have a certain kind of narrative punch that D&D is OK with encounters NOT having. Fundamentally, that is a misalignment in D&D's design intent and your play intent. You can tweak D&D until it suits you, but the basic design of the thing is not intrinsically better if you remove save or suck spells. Might as well remove surprise or stealth while you're at it, and maybe get rid of PC death and crits and...