How do you set difficulties though?

And do you use spellcraft skill checks?

Do you remove saves and the possibility of spell resistance? If not, you're unfairly penalizing spellcasters in your game. They're already balanced by the inclusion of the save and SR mechanics - adding another is like making a Fighter roll a miss chance % on every hit.

I have always favored a Roll-to-Cast system. I never understood why you have to roll a D20 to do EVERY OTHER GODDAMNED THING IN THE SYSTEM except spells.

This is because spells are a limited-use commodity in D&D and already balanced by at least one die roll whenever an opposing character is targeted.

Take a look at Rays -- they require attack rolls, but never a saving throw (when designed properly.) Imagine how the game would run if it wasn't so. Imagine the headache when your new player finds out how useful his disentigrate spell is, and casts it against the Dragon the party's fighting at night, on a rocky sea.. Let's see...

1: PC Rolls d20+Con to manage to cast the spell...
2: PC Rolls d20+cast to cast the spell.
3: PC Rolls d20+atk to hit dragon with ray
4: DM Rolls % Miss Chance
5: PC Rolls d20+cast to overcome Spell Resistance
6: DM Roll d20 + Fort for Saving Throw.
7: PC Rolls 1d6 for residual damage.

The game just doesn't play well when a single action can potentially cause six die rolls, only to have no effect.

Now, a nice Roll-to-Cast system that rolls up Rays and Concentration into the roll, and folds Spell Resistance into the saving throw, could be downright cool...

I was just looking at the Truename stuff out of the new Tome of Magic, which uses a roll-to-cast system in place of the limited-use aspect (which I think I like, as it does save you the headache of having to remember how many spells you've cast today, or within the past 8-hours when you're attacked at night). It at least moves the concentration stuff into the roll.

You could say that Spell Resistance doesn't need to be folded into the roll, because it isn't always (or even that commonly depending on your game) a factor. Like is it that bad if once a session the player has to roll an extra check to overcome spell resistance, just like if once a session the player has to roll to avoid a miss chance?

Of course, that doesn't answer the question of rays... of course depending on your system, spells could require that extra roll because they're that much more powerful (like the fighter rolls once to do 1d6 dmg, the wizard rolls twice to do 2d6 or 3d6 damage).

Do you have any suggestions for roll-to-cast systems? I kind of like the idea, if only because it makes magic seem more difficult and significant when you use it.