If you're playing Apocalypse D&D, here are some new rules for spellcasting you might want to try out.
PDF version is available here:
http://planet-thirteen.com/apocD&D/spellcasting%20Update.pdf, feedback is welcomed!
Instead of memorizing spells, spellcasters prepare some of their spells for faster casting. They may prepare the same number of spells they could memorize under the D&D rules, but these spells are not forgotten. With a night's rest, they can change the spells they have prepared. A spellcaster may also cast spells they have not prepared, using the Focused Casting move.
Cast a Prepared SpellWhen you make a move by casting a spell you have prepared, make that move as normal. For example, if you go aggro using Magic Missile as your weapon; Make your Move using Jump; read a situation using Scry, and so on.
On a 10+: the spell works as written with no difficulties
On a 7-9: in addition to any options they already get, the DM may choose to roll on the miscast table.
On a miss, the DM decides what happens, as normal.
Focused CastingWhen you take out your spellcasting accouterments and spend several minutes casting a spell you have not prepared, or cast a prepared spell without making any other move, roll dice. Magic Users and Illusionists roll +INT. Druids, Clerics, Rangers, and Paladins roll +WIS.
On a 10+: Choose one:
• Maximize dice
• Extend range, duration, or number of targets times two
• Cast covertly, without sound gesture or outward sign
On a 7-9: The spell goes off as normal, but the DM chooses one effect in addition:
• Someone’s exposed to danger
• Someone’s put in a tight spot
• Someone or something is made aware of the casting
• Roll a miscast
Miscast Table1. The casting is accompanied by annoying, but otherwise insignificant effects like the smell of sulfur or the sound of tinkling bells.
2. The caster’s appearance or body is altered in some alarming way (but it goes away in a few hours).
3. The caster’s vicinity is visited with frightening manifestations of wild magic, divine disfavor, infernal wrath, or inimical forces of mysterious origin.
4. The caster’s appearance of body is altered in some alarming way, and it’s permanent.
5. The caster or target immediately has their mind opened to contact some higher or lower power.
6. The caster or target is incapacitated by magical feedback. Immediately take s-harm (when you take s-harm, in order to do anything but wander around in a daze, you must successfully Defy Danger).
7. The spell is accompanies by drastic and uncontrolled pyrotechnics, noise, or other distracting effects. Everyone in the area of effect must roll to Defy Danger to do anything but duck and cover for the next round.
8. The spell echoes across the eternal flows of magical essence. Every powerful magic or divine being in the vicinity senses the cast and knows who cast it.
9. The spell exposes the caster and/or allies to harm or danger as per the spell’s effect (or, if beneficial, reversed effects). Normal saving throws apply.
10. A small rift is opened in the planar fabric and something or someone comes through.
Saving ThrowsWhen you make a saving throw, roll dice:
• If it’s paralyzation, poison, or death magic, roll +CON
• If it’s petrification or polymorph, roll +STR
• If it’s rod, staff, or wand, roll +WIS
• If it’s breath weapon, roll +DEX
• If it’s spells, roll +INT
On a 10+: You escape or resist to no ill effect
On a 7-9: You take half damage, are exposed to greater danger, or put in a tight spot.
On a miss, you suffer the full effects.