As I think over the proposed setup from the OP there, I have already begun to modify it.
Each magic user rolls a dice per level to see how many "magic points" they have to allow for spell casting energy.
The level of the spell determines how many points are deducted from the total per spell used. Thus, a first level spell deducts one point from the total and second level spells remove two points from the total, etc...
A magic users Intelligence or Wisdom score will determine the maximum ability of the spell casters spell availability.
For example, a magic user with intelligence of a 15 can have a maximum of 11 spells per level and a minimum of 7 spells. Of course, magic users are still subject to having to search and obtain the spells to begin with. Though I would allow them to start with more than one spell in their spell books from their Master. Maybe 2. Clerics and druids already start with 2 spells as it is.
Druids and clerics, because they get a bonus based on Wisdom, will have to obtain spells as normal, though again, starting with a couple more than the book stipulates.
The poster in the thread says he uses 1d6/level to determine "magic energy points". That would be fine, but I think somehow it also should be tied to maybe their Constitution scores.
Perhaps using Constitution score levels to use a different die like:
- 1 to 14 use 1d4/level
- 15 to 18 use 1d6/level
Also, it only seems reasonable that cumulative total "magic points" cannot exceed total Constitution score. So, if a spell casters Constituiton score is 15, once their magic points reaches 15, that's it. They can gain no more magic points. To exceed more than ones energy/life force, one would die. So, in a way, a spell caster's magic using ability is essentially using their personal energy.
I know that BtB, a spell casters spells are said to not be tied to their own energy, but tied into some "other" realm for the energy of their spells. My point system kind of takes that half and half. While the force/capacity of the spell in question does not hinge on the magic users own energy, the energy required to focus, concentrate, and "direct" the spells still pulls a drain on the spell casters personal energy.
To me this has a lot of potential though.
Zero level spells(cantrips) still are totally usable as they consume zero points from total.
After that, spellcasters get to use more than one spell per day (depending on their roll/level and level of spell)
This seems easier to manage than the other system I created and stays true to character ability scores.