Thoughts on wild magic

Though it's not a class I've ever seen used in practice, I've always been smitten with the idea of the wild mage -- a magic-user who lives on the dangerous and unpredictable side of the arcane. The only place I've actually seen a wild mage class presented was in the AD&D 2nd edition Tome of Magic. The class didn't appear in AD&D 1e (as far as I know) and also seems to have never made it into the later versions of the game (again, as far as I know -- please correct me if I'm wrong here).

This lack is something I hope to remedy by including guidelines for wild magic in my work-in-progress book.

My initial thoughts are going along a different track to the ToM wild mage, which presented a d100 table of (fairly extreme) wild surge effects, with a 1 in 20 chance of a wild surge occurring each time the wizard casts a spell. Personally, I'd like a system where wild surges are more common but less extreme. And instead of the fixed table of effects, I'd like to design a system which taps the endless (d∞!) creative potential of the DM & players. So here are the beginnings of my thoughts on how this might work.

The basics

• Any magic-user can choose to be a wild mage. Usually this choice would be made at character creation, and could never be altered, but existing MUs may be allowed to opt to be wild mages if the DM introduces the option in the middle of a campaign.
• Magic-user sub-classes like illusionists can also opt to be wild mages (or wild illusionists, in this case).
• Whenever a wild mage casts a spell, the player must roll 1d6 & 1d12. The d6 determines whether a wild surge occurs, which is indicated by an odd number. If a wild surge does occur, then the d12 indicates what happens.

Table 1, 1d6

1. Wild surge, consult table 2.
2. Spell works as intended.
3. Wild surge, consult table 2.
4. Spell works as intended.
5. Wild surge, consult table 2. Spell remains in memory (can be cast again).
6. Spell works as intended plus stays in memory (can be cast again).

Table 2, 1d12

1. Spell functions as if the caster were 1d4 levels higher than normal.
2. Spell functions as if the caster were 1d4 levels lower than normal. (If effective caster level ends up less than one then the spell has no effect.)
3. Spell has normal effect plus the effect of a randomly chosen spell of the same level.
4. Spell has normal effect plus another randomly chosen memorized spell is activated unwillingly.
5. Spell manifests as intended and a randomly chosen spell of the same level appears in the caster's mind in its place. (The caster is able to cast this spell, even if it is not one that he usually could.)
6. Spell fizzles with no effect.
7. The spell's target or area of effect (where applicable) changes.
8. Randomly chosen spell of same level activates instead.
9. Randomly chosen spell of one level higher activates instead.
10. A randomly chosen spell of level d8 manifests instead of the intended effect.
11. Cast another memorized spell instead. (If the caster has no other spells memorized, then nothing happens and the spell remains in memory.)
12. The caster loses the ability to cast spells for 1d4 rounds or 1d4 turns (whichever the Labyrinth Lord deems appropriate).

So the main creativity of the system comes when the intended effect is replaced by a randomly chosen spell. This would require a lot of quick creative thinking on the part of the DM, which I reckon would be a lot of fun! For example, what happens when a sleep spell surges and is replaced by hold portal?. The intention is that the DM wouldn't have to follow the random spell's description to the letter, but could simply use it as a creative kick-start. In the example of sleep transmuting into hold portal, perhaps there are no doors close by, and the DM could interpret it as locking shut the mouths or eyes of all creatures in range.

As I say, this is all just a beginning, so I'd be very interested to hear anyone's thoughts on what I've described or on wild magic in general.