Spell Dice: A Magic Resource & Resolution System

[Deleted]

Let me get 2 things straight right up front. (1) I have no issue with the BtB Vancian spell system and use that system exclusively when I run games (so far, at least). You're free to assume whatever you wish but there's the true-true right there. (2) I didn't write this, I got it from Necopraxis' 'Blog. If you like this system I'm certain he'd love to hear from you. I'll even go out on a limb and say he'd probably love to hear your constructive criticism as well.

Now with that out of the way, I must say I like this alternative and am thinking of using it for an alternate M-U class, the Sorcerer, IMC.

A magic resource and resolution system:

Magic-users get 2 + level six-sided spell dice.
Any number of spell dice may be used to cast a spell.
Casting a spell successfully requires rolling 7 + spell level or higher.
Any die that comes up 1 or 2 is removed from the pool.
All spell dice are recovered following a restful night of sleep.

This method is separate from the approach used for deciding which spells are available for casting and could be used with any spell preparation scheme, including the traditional complicated collection of level-based slots, or something simpler.

For example, a third level magic-user has 2 + 3 = 5 total spell dice. This magic user attempts to cast a second level spell, which has target number 7 + 2 = 9. Three spell dice are committed and rolled, yielding 2, 4, and 5, with a total result of 2 + 4 + 5 = 11, which is enough to cast the spell. One of the dice came up 2, however, and so is removed from the pool, leaving the magic-user with only four dice for future spells.

This would work with level-agnostic spells. Just treat every spell as level 1 (meaning the target number is a flat 8).

The scarcity of magic can easily be adjusted by changing the number range which removes dice from the pool (specified above as die results of 1 or 2).

Any number of other bonuses could be factored into the spell roll, but any math beyond the calculation of the initial target number (7 + spell level) will make the procedure for casting spells feel more cumbersome in terms of game mechanics.

The above rules are the minimum required to make the basic system work, but there are several other details which would add to the system.

Empowerment

If the spell fails with a result that includes snake eyes (two or more 1s), the outcome is a magical catastrophe (with effect appropriate to the spell in question). If the spell succeeds with a result that includes boxcars (two or more 6s), the spell is cast with greater effect than normal (increased range, more enemies affected, extra damage, or something similar).

As the number of dice recruited rises, so does the chance of rolling either snake eyes or boxcars. This is thematically appropriate, given the idea of drawing on more unstable power at once. The chance of either extreme result is 1 in 36 (approximately 2.7%) for two dice, 16 in 216 (approximately 7.4%) for three dice, 171 in 1296 (approximately 13%) for four dice, and chances continue to increase. This is a binomial distribution.

Using Life Energy

When spell dice resources are depleted, magic-users can also draw on their own life essence to fuel spells. Life energy dice may be used, but they deal damage to the magic-user whether or not the spell is successful. The number of life energy dice usable at one time may not exceed the magic-user level. Care should be taken with this option based on the availability of healing, as any effect that can restore HP can also be used to power spells, and healers may become spell batteries. Life energy dice are always expended when used.

Encumbrance

It would be reasonable to apply armor penalties to any spell roll total if armor is not restricted by class. Similarly with encumbrance penalties if encumbrance is tracked.

This is a mutation of a system described by Courtney. The major changes are that there is no fivefold results table (allowing the system to be used without any lookups) and here higher spell level makes spells harder to cast successfully whereas Courtney’s system makes casting high level spells more likely to exhaust dice. I have also been informed that Courtney has simplified the results from fivefold to threefold:

1-5: spell goes off at the end of the round, lose the spell.
6-8: spell goes off at the end of the round.
9-12: spell goes off instantly.

It is also an example of concentric game design (the first five points are necessary while everything else is supplementary).

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Based on discussion here and here, I am concerned that an unlucky first-level magic-user might not be able to get off any spells successfully before exhausting all the dice (this would happen about 15% of the time, assuming that life energy is not used, according to Ian B.’s numbers, if any die that comes up 1 or 2 is always removed from the pool). That’s no good. This could be somewhat mitigated by starting off beginning magic-users with more than 2d6 base spell dice. However, I think a better solution would be to only exhaust dice on either successfully casting a spell or failing with a catastrophe. That way, any given spell casting would not be guaranteed, but magic-users would not expend dice without also producing some sort of effect (either good or bad).

[Deleted]

7+Spell Level might be too low considering a 9th level spell would be 16+ and a 10th level magic-user will have 12 dice. One thing to consider is saving throws. If you combine a spell casting roll alongside a saving throw, you've decreased the effectiveness of the spells. So it might be wise to include the save as part of the spell die roll and, thus, have the target number increase based on the target of the spell.

However, I think this idea would work best if the individual spells had variable target numbers based on effect. A sleep spell could increase the number of targets, a fireball increase the number of dice and a charm person the target number increases based on the power and number of charmed opponents (as above). This would give the cast two choices; first in how many dice to roll and second how powerful a spell to attempt.

Finally, you could also give individual spells their own Fatigue number. So simple spells, like Light, might only cause the loss of a die on a 1 (even 0 is possible) so can be cast over and over, whereas extreme spells like Raise Dead could have a Fatigue of 5. Encumbrance could modify Fatigue so armor wearers can cast spells just not as many.

[Finarvyn]

A neat concept. I haven't run the numbers as much as hedgehobbit, but he seems to have a valid point. I suspect we could work around that with a simple tweak, however, such as only allowing casters to cast spells of a level equal to their own (or something like that).

This might mean that a 9th level MU could cast a 9th level spell, but maybe that wouldn't be a bad thing if he had to use up most of his dice to do so.

[Finarvyn]

Okay, more thoughts on this. I did some quick spreadsheet calculations to determine how many dice would be needed (on the average) in order to cast a particular spell. Let me know if my reasoning is faulty.

Consider a MU casting a 1st level spell, which would have a target number of 8. I calculate that if each die rolls an average number of 3.5, then the MU would have to spend on the average 2.3 dice in order to cast the spell. But 1's and 2's get thrown out so the long-term "value" needed is really around 1.5x the number of dice needed, or 3.4 dice. (Basically, he needs to roll 2.3 dice but loses 1.1 of those dice in the process.)

On the other extreme (again, assuming that my logic isn't faulty) casting a 9th level spell (TN of 16) only requires 4.6 dice, with an estimated loss of 2.3 dice in the roll, for a total "value" of 6.9 dice.

I sort of like the attrition rate, since it has a long-term effect of running out of spells, but I'm not sure that the Target Numbers work right.

Still a cool concept. Must ponder further.

[Deleted]

Since each new die adds 3.5 to the average total if the player were to roll all the dice, if you scale the target number to this number they will quickly get out of control. So I suggest each character having two number; a Power value which is how many dice the magic-user has in total and a Control value which is the maximum number of dice a player can roll at one time. A character's Power will roughly determine how many spells he can cast and his Control will determine his maximum spell level.

A magic user will start with a Control of 2 + his Int modifier and a Power of 2 + his Charisma (or Wisdom if you prefer) modifier. A character can gain +1 to either value every level including first.

With this method, player have a way of customizing their magic user characters focusing on lots of low level spells or a few high level spells.

[Ynas Midgard]

I created a small program to simulate such casters; below, I present you my findings, gathered from 100,000 simulations for each row. I assumed casters devote a number of their spell dice to casting a spell of a given level ("X spell dice used"); they tried to cast it until it became impossible for them to do so (i.e. they ran out of dice).

The first number after "=" means the average number of successful repeated spellcasting attempts, whereas the number in parentheses, really just for fun, shows you the greatest number my fictitious spellcasters could cast a given spell repeatedly.

Note: Even if the number of available spell dice decreased below the initially committed amount, they continued as long as there was still chance succeeding.

Caster Level 1, spell level 1:

[*]2 spell dice used = 1.34429 (15)
[*]3 spell dice used = 1.65814 (16)

Caster level 1, spell level 3:

[*]2 spell dice used = 0.54264 (9)
[*]3 spell dice used = 1.07164 (11)

Caster level 5, spell level 3:

[*]2 spell dice used = 1.5408 (13)
[*]3 spell dice used = 3.54543 (18)
[*]4 spell dice used = 3.78702 (15)
[*]5 spell dice used = 3.47051 (14)

Caster level 5, spell level 5:

[*]2 spell dice used = 0.25894 (6)
[*]3 spell dice used = 2.03316 (13)
[*]4 spell dice used = 2.9264 (13)
[*]5 spell dice used = 2.90239 (12)

[barrataria]

This is interesting, mostly because you could drop it right into d6 Fantasy and give it a nice simple magic system that would dovetail with the rest of the game.

[Deleted]

Did some calculating. With dice fatiguing on 2 or less, each dice will, on average, be rolled 3 times. So a character with 9 spell dice will end up rolling 18 dice before running out.

Using spell dice will also solve a problem I've had with D&D for a long time with how magic wands work in D&D compared to the rest of fantasy fiction. So, here's what I've some up with:

-A minor magic wand will allow the caster to reroll 1s on his casting roll.
-A major wand will allow rerolls on 1s and 2s.
-If the wand has a specific "school", rerolls with that school will be one better. So a minor wand of necromancy will allow rerolls of 1s and 2s on necromantic spells and 1s on other spells.

-An Elder Wand call reroll 1s, 2s, and 3s and would be a pretty powerful artifact.

This will increase the number and average rolls of the caster without increasing his maximum possible roll. So a wand user will be able to cast longer and with less chance of a fumble. Disarming a wizard will weaken him but not overly much. A wizard can only have one wand at a time as it takes several months to attune one. If you are a Harry Potter fan, you can have some rolls to determine if the wand accepts the caster otherwise it will operate in a lesser manner.

Finally, a wizard on the receiving end of magic can dispel by rolling his spell dice and trying to beat the number of the enemy wizard. A wizard can passively use 1/2 his Control value (or level if you wish) automatically without that counting as an action. A wizard that is doing nothing but dispelling, can use his full number of dice. Dice use to dispel fatigue in the normal manner.

[Deleted]

I've been developing this idea (which isn't even mine) a bit more. One of the ideas is the concept of using spell dice to Bind a spell. When a spell of a duration other than instant is cast, the spell caster must allocate a number of dice to keep that spell active. This will range from 1 for a low level spell that typically has a long duration (like Light) up to 3, 4 or even more. When the die is Bound to a spell, that dice cannot be used for casting and is, in effect, removed from the caster's pool limiting his normal casting. The spell will last as long as the number of dice required are Bound to it. This allows the caster to keep a certain number of "buff" type spells always on, giving each wizard a chance to have his own repertoire of powers; such as magic armor/shields or the ability to fly, but at a cost of his own flexibility. It also will naturally lead to the crumbling wizard tower Trope as all of the wizard's spells will end when he dies.

[jeff]

Dec 30, 2013 14:35:28 GMT -6 @hedgehobbit said:

I've been developing this idea (which isn't even mine) a bit more. One of the ideas is the concept of using spell dice to Bind a spell. When a spell of a duration other than instant is cast, the spell caster must allocate a number of dice to keep that spell active. This will range from 1 for a low level spell that typically has a long duration (like Light) up to 3, 4 or even more. When the die is Bound to a spell, that dice cannot be used for casting and is, in effect, removed from the caster's pool limiting his normal casting. The spell will last as long as the number of dice required are Bound to it. This allows the caster to keep a certain number of "buff" type spells always on, giving each wizard a chance to have his own repertoire of powers; such as magic armor/shields or the ability to fly, but at a cost of his own flexibility. It also will naturally lead to the crumbling wizard tower Trope as all of the wizard's spells will end when he dies.

Very cool ideas hedgehobbit! I love it!

[sulldawga]

Dec 30, 2013 14:35:28 GMT -6 @hedgehobbit said:

I've been developing this idea (which isn't even mine) a bit more. One of the ideas is the concept of using spell dice to Bind a spell. When a spell of a duration other than instant is cast, the spell caster must allocate a number of dice to keep that spell active. This will range from 1 for a low level spell that typically has a long duration (like Light) up to 3, 4 or even more. When the die is Bound to a spell, that dice cannot be used for casting and is, in effect, removed from the caster's pool limiting his normal casting. The spell will last as long as the number of dice required are Bound to it. This allows the caster to keep a certain number of "buff" type spells always on, giving each wizard a chance to have his own repertoire of powers; such as magic armor/shields or the ability to fly, but at a cost of his own flexibility. It also will naturally lead to the crumbling wizard tower Trope as all of the wizard's spells will end when he dies.

Do Bound dice return to the casting pool once the active spell is dismissed?

[Deleted]

Jan 13, 2014 12:58:14 GMT -6 sulldawga said:

Do Bound dice return to the casting pool once the active spell is dismissed?

Yes. It has to be a normal non-fatigued die to begin with. I contemplated fatiguing them but decided against that since a normal instantaneous spell doesn't fatigue extra dice.

A couple other things. Firstly, if a non-magic-user character has a bonus from both his Int and Cha, then he will have a small magic dice pool equal to his Cha modifier and a Control value equal to his Int modifier. He will be known as a Dabbler and can cast the wimpiest spells since he will generally only have one or maybe two dice. To have three dice you would need a 18 Int and an 18 Charisma on top of whatever the prime requisite was in your class. So munchkins only.

I'd like to have some sort of effect where it increases or decreases the size of the dice. For example, an area can have strong magic, increasing the dice from d6s to d8s or weak magic dropping them to d4. I'd also like some sort of magical items which increase a certain number of dice but don't know what they should be. I will probably end up having certain magic staffs Empower a certain (small) number of dice.