I've come to the conclusion that the next campaign I run, regardless of system (though who am I kidding, it will be an OSR / Earlier D&D system) I'll be putting more power into the hands of the players. Note - not the PCs themselves. I just want to move some things that are normally on the DM's side of the screen to the Players' side of the screen. (I'm sure this has been done before, but it's the first time for me)
The main thing is to put some of the rolls the DM makes into the hands of the players. The first thing (and main thing in my mind) is Monster Saving Throws - in particular Spell Saves. I want to turn that into a spell attack roll of sorts, but the difficulty is based upon the HD of the monster, not the level of the PC (although we could tweak that slightly if we wanted to).
It's simple enough to turn the saves into a roll high attack for PC casters. I'm going to use S&W Whitebox for the sample table.
Saves for monsters in S&W WB are determined by subtracting the monster'sHD from 19. So, a 2nd level monster has a save of 17. Simple enough. To turn that into an attack roll, we start from 2 and add the HD.
For example, a PC magic-user would need to roll a 6 or better to successful cast a spell on a 4th level creature (2 + 4 (from HD)). A 1st level creature would need a roll of 3 or better for the PC's spell to be successful.
Simple enough. No longer is it in the DM's hands if the player's spell is successful or not - it lies in the hands of the players now.
Using this system, you could also add an optional modifier based on level comparison if you desired: if the PC is higher in level than the creature's HD, he can add +1 to the spell attack roll. Same level means no bonus. If the PC is lower in level than the target's HD, he has a penalty of -1 to his spell attack roll.
I think it makes sense putting the resolution of caster's spells in the hands of players. Combat resolution of the players' attacks have been in the hands of the players since the game started, why not spells?
Note, this doesn't change how players save against spells cast on them - the point is to put more of the game resolutions in the hands of the players, not remove it.