The Mana System is a supplement for replacing the CASTING of spells per day with mana. It allows a character to be more flexible with their spellcasting and alleviate the loss of lower level spells that they may not use except in specific circumstances. All other rules still apply, such as choosing which spells to cast for the day, etc.
The mana pool is refreshed at the beginning of each day when the character prepares her spells for that day unless otherwise specified by the DM. Characters’ spell levels are still dependent on their level (for instance, a 12th level sorcerer can cast up to 6th level spells, nothing higher).
Characters gain mana per level as they would gain spells per day. The cost to cast these spells is as follows:
- Cantrips/Orisons: 1 mana per spell.
- 1st: 2 mana per spell.
- 2nd: 4 mana per spell.
- 3rd: 8 mana per spell.
- 4th: 16 mana per spell.
- 5th: 32 mana per spell.
- 6th: 64 mana per spell.
- 7th: 128 mana per spell.
- 8th: 256 mana per spell.
- 9th: 512 mana per spell.
Metamagic feats use the appropriate mana for whatever spell slot they are pulling from (IE: Maximized Fireball would cost 64 mana since it takes a spell slot 3 levels higher, instead of 8 mana since it’s a 3rd level spell). If this seems too powerful, you could: limit the number of metamagic spells a caster can use, exercise a “drained” penalty for calling upon so much arcane power, mana could replenish more slowly the following day, etc.
If a caster gains extra spells per day as based on a high ability score, these extra spells are converted to mana as appropriate. (For instance: Durgranahk is a 1st level cleric who has a Wisdom score of 18, thus giving him an extra 1st level spell per day. He takes is base total on the chart below (7 mana; 3 mana for three orisons, 2 mana for his 1st level spell and 2 mana for his domain spell) and adds 2 mana for the extra 1st level spell per day for a total of 9 mana.
As it stands, a high level magic user has seemingly infinite access to lower level spells. If this does not appeal to your sensibilities, you could limit how much mana can be spent on lower level spells.
To calculate the mana pool a class not listed would gain per level, simply take their spells per day for each level and multiply each spell level by the appropriate mana cost to cast. Then, add these totals together.
For instance: An assassin at 10th level gets three 1st, three 2nd, three 3rd, and three 4th level spells per day. A 1st level spell costs 2 mana to cast, so 3×2=6. A 2nd costs 4 mana; 3×4=12. 3rd level costs 8 mana; 3×8=24. 4th level costs 16 mana; 3×16=48. So, if we total each of these, we find the assassin has a base mana pool of 90 (which, coincidentally, lets him cast 3 spells of each level he would have access to anyway).