D&D 3.x was developed with the expectation of 4 encounters per day. Often, you will want to run with a different number of encounters. In a dungeon crawl, nobody likes it when the spell casters want to quit for the day at noon because they're out of spells. If the party is making a 4 day trip through a dangerous (but CR appropriate) region, 4 encounters per day means they level just off the random encounters in the trip. A DM could want to put just two or three encounters in that trip, which makes if feel dangerous, but not give a whole level of XP (and possibly spend a month of real-time playing out the combat).
I'm considering the following house rules for my next game. The game will be at levels 1-6, but I'd prefer if the rules would also work at higher level.
1. Per day limits of spell slots and power points apply as usual, except as modified below.
2. In each encounter, a character may use at most 1/3 (round up) of his spell slots at each level or power points.
3. After the fourth and each subsequent encounter, the per day limits increase by 25% (no rounding) of the base value.
My reasoning is as follows.
By keeping the per day limit, you avoid problems like the wizard casting shield every (caster level) minutes, effectively boosting the duration from minute/level to permanent.
A strict rationing scheme would use a per-encounter limit of 1/4. Using 1/3 means your limited to about the amount you would use if you were expecting 4 similar encounters, but it allows you to splurge a bit, if you think this is a tough encounter. This addresses days with "too few" encounters.
Days with "too many" encounters require extra resources. This grants extra resources, in proportion to how many extra encounters there are. The lack of rounding means that there's still a difference between 4 spells per day and 7 spells.
As an example, consider Wally the Wizard. Wally can cast 3 second level spells and 5 first level spells. Wally wakes up and, just before going out with his friends, casts Mage Armor on himself. A while later, the party is attacked by an ogre. During the fight, Wally can cast 2 (5/4 rounded up) first level spells and 1 (3/4 rounded up) second level spell. He casts Shield, Magic Missile and Acid Arrow, using all three of those spells. He has now cast 3 1st and 1 2nd level spell.
A bit later, the party is attacked by a small horde of kobolds. He again can cast 2 1st and 1 2nd level spells. A pair of sleep spells ends the battle. Wally has now used 5 first level spells and 1 second level spell.
Shortly thereafter, another ogre finds the party (encounter 3). Wally now feels the pain of his early spell use, since he can't cast any first level spells, having already cast the 5 that he knows. After casting Melf's acid arrow, he's going to have to decide whether to fall back on cantrips or his cross bow.
During the fourth encounter, Wally realizes his remaining second level spell won't affect the opponent, so he sticks to the crossbow and scrolls. After this fourth encounter ends, his spells per day increase to 6.25 1st and 3.75 second. If there's another encounter, he'll have 1 first level spell (from the 25% increase) and 1 second level spell (uncast from his original 3). At the end of that encounter, his spells per day will be 7.5 and 4.5, so he'll gain a first and second level slot.
Here are some potential issues that I see. Enemies that don't have limits and are an above average difficulty are much more dangerous. Spellcasters can't burn through everything at once if they need to, so a "climatic" encounter, with an EL of party level + 4, is likely to be a TPK if the enemies are unaffected by this rule (most likely by being fighter types).
It needs clarification for prepared spellcasters that gain additional slots. Are they filled with copies of spells that were memorized earlier or empty? I'd probably let the player pick.
Encounters with waves of attackers might need to be declared multiple encounters. If the 5th level party meets an EL 3 enemy, nearly defeats it when EL 3 reinforcements arrive, followed by more EL 3 reinforcements when those are almost dead, the spellcasters are probably going to run out of spells well before the last batch is defeated. This can probably be dealt with just by the GM being aware of the problem and declaring a "new" encounter at appropriate points.
Other per day abilities might want to be handled similarly, but I'm not certain. If you're fighting undead and the cleric is being successful with his turning, he probably wants to use as many as he can, since the remaining combats could easily have no undead. Smiting and stunning fist also may have encounters where they are completely useless.
Questions or criticisms?
I'm considering the following house rules for my next game. The game will be at levels 1-6, but I'd prefer if the rules would also work at higher level.
1. Per day limits of spell slots and power points apply as usual, except as modified below.
2. In each encounter, a character may use at most 1/3 (round up) of his spell slots at each level or power points.
3. After the fourth and each subsequent encounter, the per day limits increase by 25% (no rounding) of the base value.
My reasoning is as follows.
By keeping the per day limit, you avoid problems like the wizard casting shield every (caster level) minutes, effectively boosting the duration from minute/level to permanent.
A strict rationing scheme would use a per-encounter limit of 1/4. Using 1/3 means your limited to about the amount you would use if you were expecting 4 similar encounters, but it allows you to splurge a bit, if you think this is a tough encounter. This addresses days with "too few" encounters.
Days with "too many" encounters require extra resources. This grants extra resources, in proportion to how many extra encounters there are. The lack of rounding means that there's still a difference between 4 spells per day and 7 spells.
As an example, consider Wally the Wizard. Wally can cast 3 second level spells and 5 first level spells. Wally wakes up and, just before going out with his friends, casts Mage Armor on himself. A while later, the party is attacked by an ogre. During the fight, Wally can cast 2 (5/4 rounded up) first level spells and 1 (3/4 rounded up) second level spell. He casts Shield, Magic Missile and Acid Arrow, using all three of those spells. He has now cast 3 1st and 1 2nd level spell.
A bit later, the party is attacked by a small horde of kobolds. He again can cast 2 1st and 1 2nd level spells. A pair of sleep spells ends the battle. Wally has now used 5 first level spells and 1 second level spell.
Shortly thereafter, another ogre finds the party (encounter 3). Wally now feels the pain of his early spell use, since he can't cast any first level spells, having already cast the 5 that he knows. After casting Melf's acid arrow, he's going to have to decide whether to fall back on cantrips or his cross bow.
During the fourth encounter, Wally realizes his remaining second level spell won't affect the opponent, so he sticks to the crossbow and scrolls. After this fourth encounter ends, his spells per day increase to 6.25 1st and 3.75 second. If there's another encounter, he'll have 1 first level spell (from the 25% increase) and 1 second level spell (uncast from his original 3). At the end of that encounter, his spells per day will be 7.5 and 4.5, so he'll gain a first and second level slot.
Here are some potential issues that I see. Enemies that don't have limits and are an above average difficulty are much more dangerous. Spellcasters can't burn through everything at once if they need to, so a "climatic" encounter, with an EL of party level + 4, is likely to be a TPK if the enemies are unaffected by this rule (most likely by being fighter types).
It needs clarification for prepared spellcasters that gain additional slots. Are they filled with copies of spells that were memorized earlier or empty? I'd probably let the player pick.
Encounters with waves of attackers might need to be declared multiple encounters. If the 5th level party meets an EL 3 enemy, nearly defeats it when EL 3 reinforcements arrive, followed by more EL 3 reinforcements when those are almost dead, the spellcasters are probably going to run out of spells well before the last batch is defeated. This can probably be dealt with just by the GM being aware of the problem and declaring a "new" encounter at appropriate points.
Other per day abilities might want to be handled similarly, but I'm not certain. If you're fighting undead and the cleric is being successful with his turning, he probably wants to use as many as he can, since the remaining combats could easily have no undead. Smiting and stunning fist also may have encounters where they are completely useless.
Questions or criticisms?
