D&D General + Homebrew Brainstorm to bring back prepared Vancian Casting +

[el-remmen]

B. you always successfully cast, but you're rolling to see if you keep the spell. So you could potentially get multiple casts out of one prepared spell, but preparing it multiple times would mean greater guarantee on being able to use that spell consistently.

I use the above in my OSR homebrew rules.

I do something similar, but just for cantrips. Cantrips are unlimited unless you fail the spell check roll upon casting it, in which case it still goes off, but you lose access until after a Long Rest. However, you may spend a spell slot to cast a cantrip with no chance of failure. The fail chance is fairly easy, but not a given. d20 + Prof Bonus + spell casting mod vs. DC 11 (nat 1 being auto failure).