|From Warlock (1975), pages 6-7|
When Warlock was published the only published D&D books were the original set and the Greyhawk supplement, both of which it references. Now that these first two publications are available again as pdfs, it is a good time to go back and take a look at this spell point system that Holmes was a fan of. The presentation in Warlock is a bit scattershot, like the OD&D rules themselves, so I've tried to re-organize it here.
Above I've quoted a bit of Warlock's theory behind using spell points: M-U spells have two qualities, complexity (level) and effort required (spell points). Thus each spell is additionally assigned a spell point usage cost.
The basic formula:
Spell Points (SP) per day = Hit Points + Level + Int modifier
16+ : +1 point per HD
13-15: +1/2 point per HD
Note the HD system in Warlock is similar to the original d6-based HD system, with a M-U only getting a full d6 HD every other level. So HD here is not the same as Level.
Note also that Warlock uses the original OD&D Con modifier to HP (Con > 15 = +1 HP/HD, Con < 6 = -1 HP/HD), so a high Con only gives a small bonus to spell points.
Example (from pg 6):
A 5th level M-U (3d6 HD) with 9 HP with an average Int = 14 SP
"Life-Saving Margin": A M-U can exceed the SP only to safe own life. This extra margin is the same as the character's "Death Level", which is the number of HP between unconsciousness and death (i.e., the "death's door" rule in later systems).
The calculation for the "Death Level" is explained in the section on combat (pg 29) and uses a complex formula: .03 x HP x CON score. The example given is a 10 HP character with 15 CON, yielding a 4.5 HP "Death Level" (.03 x 10 x 15), meaning the character can go to -4.5 HP before dying.
Spell points get the same margin as Death Level, but when M-Us go below it they suffer the following consequences in lieu of dying: unconsciousness for d6 turns, movement slowed by one step, and loss of all other casting for the day (i.e., since they have no spell points left).
Memorization rules: This system is not "free casting". Despite having spell points, a M-U can still only cast based on what spells are known, and what is memorized. At lower levels, the memorization tables are the same as OD&D; e.g. a 1st level MU can memorize one 1st level spell/day; a 3rd level M-U can memorize two 1st level and one 2nd level spells. Higher levels have some changes and go all the way up to level 40 (!).
Warlock does not include the "% chance to know" table from Greyhawk, but does suggest limiting available spells: "In beginning a series of games it is worthwhile to limit the spells available to magic-users. This gives them incentive for finding the lairs of hostile magic-users (in order find books of spells) or researching new spells" (pg 8).
Spell Point Cost for Individual Spells for Levels 1-3:
Warlock adds many spells to each level, but I've only listed the LBB & Greyhawk spells. Warlock mentions that they have only included some of the Greyhawk spells; others have their level changed. Obviously this system was first worked out for the original spells and the new Greyhawk spells provided some complications.
OD&D Vol 1 original list:
Detect Magic 1
Hold Portal 3
Read Magic 1
Read Languages 1
Charm Person 4
Shield -- (not included)
Magic Missile 4 +1/missile (changed to Level 2)
OD&D Vol 1 original list:
Detect Invisible 2
Levitate 4 + 1/turn
Phantasmal Forces 4
Locate Object 4
Wizard Lock 6
Detect Evil 1
ESP 2 + 1/turn
Continual Light 5
Darkness, 5' r. 3 + 1/turn
Strength 7 (changed to level 4)
Web 5 (changed to level 3)
Mirror Image 5 + 1/turn (changed to level 3)
Magic Mouth 3 +1 /turn (changed to level 3)
OD&D Vol 1 original list:
Fly 5 + 1/turn
Hold Person 5
Dispell Magic 5
Clairvoyance 3 + 1/turn
Clairaudience 3 + 1/turn
Fire Ball 6
Lightning Bolt 5
Protection/Evil 10' r. 4
Invisibility 10' r. 5
Slow Spell 5
Haste Spell 5
Protection/Normal Missiles 4
Water Breathing 4 +1/turn
Explosive Runes -- (not included)
Rope Trick 6 +1/turn
Suggestion -- (not included)
Monster Summoning I -- (not included)
M-U Level/HD/Average HP/Average SP (not including any bonuses for Int/Con)
1/ 1d6/ 3.5 / 4.5
2/ 1d6+2/ 5.5/ 7.5
3/ 2d6/ 7/ 10
4/ 2d6+2/ 9/ 13
5/ 3d6/ 10.5/ 15.5
6/ 3d6+2/ 12.5/ 18.5
7/ 4d6/ 14/ 21
8/ 4d6+2/ 16/ 24
9/ 5d6/ 17.5/ 26.5
10/ 5d6+2/ 19.5/ 28.5
A 1st level M-U will have an average of 3-4 HP, and thus 4-5 spell points (SP), with a potential max of up to 9 spell points (6 for HP + 1 for high Con + 1 for Level + 1 for high Int). A single 1st level spell can be memorized. An average MU will be able to cast one of the of the more powerful 1st level spells (Sleep, Charm Person), but an above average MU with more points may be able to cast one of these spells twice. Detect/Read Spells that only cost one point may be cast multiple times if chosen as the memorized spell.
A 3rd level M-U will have an average of 7 HP, and thus 10 SP with a potential max of 19 SP (12 HP + 2 for high Con + 3 for Level + 2 for high Int). Two 1st level and one 2nd level spell can be memorized. Magic Missile is a 2nd level spell in these rules with a cost of 4 +1/missile. An average M-U can cast Magic Missile and produce 1-5 missiles for 5-9 SP. An above average M-U with 18 SP could (among other options) cast Magic Missile three times with two missiles per casting for a total of 18 SP.
Since this system layers on top of the existing memorization rules, it should be adaptable as an option for most OSR systems. It will be most easily used with systems similar to the original D&D rules (Swords & Wizardry Whitebox; Delving Deeper). Modification of the spell point formula/costs may be necessary for systems using a d4 HD and/or with higher HP and Int modifiers. A drawback is that it makes a M-U's power level much more dependent on HP rolls and Con bonuses.
The complications during play will be tracking spell points and remembering the varying spell point cost for each spell. Players should be able to write down this number next to the spell on their sheet and use it to keep track of their spell points when casting. Being able to cast additional spells will provide motivation for this extra work. It will be more of a pain for DMs because they will need to look up and track this for every NPC M-U.