As simplified as possible.
I'd do two things. First, I'd reduce the number of spells available to spellcasters. Giving them an at will attack permits this to happen more easily. Instead of carrying 15 different attack spells in the hopes that they can use each one against the idea target, the spellcaster would just have to make use of what he has. Fewer different spells memorized lets casters memorize what they actually DO use.
Second, I'd make it so that duration spells are based on concentration. I'd permit a caster to concentrate on one spell and still act freely and cast other spells. If he wanted to concentrate on a second spell, I'd start requiring die rolls if he wanted to act simultaneously. By reducing the number of active duration spells operating at one time, it reduces the amount of modifiers players have to juggle. And I'd make the duration equal to the time spent concentrating, so there'd be no paperwork on that end.
See what I mean? Joe the Wizard casts Haste. This spell lasts as long as Joe the Wizard concentrates on it. He can freely act while maintaining this spell (might make it use up his swift action or something). If he wants to cast Mass Bull's Strength on his party, he can, but if he wants to maintain both that and Haste he is reduced to a single move action per round. I might let him act beyond that, with Concentration checks.
That's just me brainstorming though.
I'd do two things. First, I'd reduce the number of spells available to spellcasters. Giving them an at will attack permits this to happen more easily. Instead of carrying 15 different attack spells in the hopes that they can use each one against the idea target, the spellcaster would just have to make use of what he has. Fewer different spells memorized lets casters memorize what they actually DO use.
Second, I'd make it so that duration spells are based on concentration. I'd permit a caster to concentrate on one spell and still act freely and cast other spells. If he wanted to concentrate on a second spell, I'd start requiring die rolls if he wanted to act simultaneously. By reducing the number of active duration spells operating at one time, it reduces the amount of modifiers players have to juggle. And I'd make the duration equal to the time spent concentrating, so there'd be no paperwork on that end.
See what I mean? Joe the Wizard casts Haste. This spell lasts as long as Joe the Wizard concentrates on it. He can freely act while maintaining this spell (might make it use up his swift action or something). If he wants to cast Mass Bull's Strength on his party, he can, but if he wants to maintain both that and Haste he is reduced to a single move action per round. I might let him act beyond that, with Concentration checks.
That's just me brainstorming though.