Two Vancian Magic Variants

Prompted by this discussion over at Jeff’s place, I had some ideas for Vancian magic house rules. Here they are again, cleaned up somewhat.

Variant 1: Spell Retention

Prepare spells as normal, standard charts. However, when a spell is cast it is not automatically wiped from the magic-user’s mind. The magic-user gets a save vs. spells (penalized by spell level) to retain it. At low levels this means that about 30% of the time spells will not be expended the first time they are cast. For powerful magic-users, it makes low level spells closer to at-will powers (but not actually unlimited). Thus, the resource management aspect of the class is not destroyed.

What’s the downside? If the magic-user rolls a 1 on the saving throw, that is considered a spell fumble and they lose the spell and must roll on a magical mishaps table (or suffer some other campaign-specific penalty). Fumbles can only occur when casting spells of the highest two or three levels that can be prepared. That is, by the time a magic-user can cast fourth level spells they have completely mastered first level spells and can no longer fumble their spell retention save. The highest level spells, however, always carry some level of risk.

Variant 2: Improv Casting

Prepare spells reliably as per the traditional rules. Any unprepared spell that the magic-user is familiar with (i.e., has in their spell book) may be cast but requires an action and a successful save vs. spells (penalty equal to spell level as above). Failure and the action is wasted, fumble and bad stuff happens. Further, a fumble occurs on any die roll equal to or less than the spell level. Thus, casting an unprepared third level spell would fumble on a roll of 1, 2, or 3. Improv fumbles should always at least prevent the magic-user from trying the same spell again until they can return to their spell books and puzzle out what went wrong.

“I saw this one thing this one time and it kinda went like this…”

Any spell that the magic-user has witnessed may also be attempted (for example, if the magic-user has seen another magic-user cast fireball). This uses the same rules as casting unprepared spells, but the save penalty and fumble threat range are doubled.

Both of these variants increase the magic-user’s power or versatility, but also expose them to fumbles. Many people prefer magic to include an element of danger, so that may be a feature rather than a bug. I like this mechanic because it is thematically coherent, is simple (no bookkeeping), and uses saving throws (which are like my favorite thing ever).

This does probably make magic-users more powerful, so if that is a problem you should control spell acquisition carefully (for example, no free new spells on level up). If one was so inclined, one could use both variants together, as they cover different aspects of casting, but that would result in a larger divergence from the traditional game.

I gather that there is a mechanic in the Dungeon Crawl Classics RPG which has a separate fumble table for each spell, so that might provide some inspiration, though a fumble table per spell seems like overkill to me.

14 thoughts on “Two Vancian Magic Variants

  1. Christopher O'Dell

    Also, I might tweak Variant 1 so that MUs only need to roll (and thus have a chance of fumbling) if they attempt to retain the spell; if they cast the spell as normal and don’t try to “hold on” to it, they don’t need to worry about fumbling and bad things happening.

  2. waywardwayfarer

    Option 2 is a lot like something I had been thinking about, but so much spiffier using the saving throw mechanic instead of an Intelligence or Wisdom check as I was pondering. I’ll probably apply the Int/Wis adjustments to the save, but otherwise this looks absolutely awesome as-is.

  3. Lum

    I use a magic fumble system where a M-U can push his luck after casting all his spells for a day. Doing so automatically triggers a roll on a magic “fumble table” of sorts. This works well in play, though I’ve thought that it’s too generous maybe. Your variant 1 seems a little less generous than mine, and variant 2 seems more generous. Hmmm. I like these, I especially like the way chance to fumble is reduced as spell caster level increases and higher level spells are more likely to be fumbled. With my system I guess more experienced Magic-Users just learn not to take stupid risks!

    Have you seen this:
    It looks like a lot of fun.

    1. Brendan

      Yeah, Mr. Orc’s system looks fun to play. It does mean that all magic-users have an expected amount of magic available before they either go insane or stop casting due to the risk of insanity.

  4. RedHobbit

    I’m really quite a fan of replicating another magic-users tricks using sight and memory alone. It’s not something you see very often and it has a lot of great potential for the MU to create a variant of the spell which might not necessarily be be for the better. Humorous things like trying to copy another Wizard’s invisibility spell but alas only your clothing disappears and bizarre things like a copied fireball that instead extinguishes flames.

    Great idea!

  5. Charles Taylor (Charles Angus)

    Cool ideas, and both could work pretty well, I think.

    Something I feel like with Alt 2, though, is that if I cast the spell spontaneously once, what is keeping me from remembering how I did that and doing it every time now without chance of failure? Or at least practicing it again and again until I’ve “got it”.

    I know that would be my first question as a player…

    1. Brendan

      Practicing the spontaneously cast spell for standard preparation sounds legit to me (assuming it was of a level that could be prepared). I would probably use the standard magic research rules for that, perhaps with a bonus or decreased cost, depending on the particular system.


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