Because people were interested in it, I thought I'd come up with a fair and 3E-appropriate way to do a wild mage in the new version of the D&D rules. I didn't want it to be silly or goofy, and I wanted it to be a class that a serious player would want to take (as opposed to the "Wahoo, I fireball everything!" sort of player). Also, because part of the D&D design philosophy is that a character's abilities should not be based on random rolls*, there shouldn't be a character class whose abilities fluctuate greatly from day to day** . With those ideas in mind, I came up with this version, which has enough randomness to make it interesting but doesn't do anything really crazy (like pull off a 9th level spell at 1st level) and doesn't have a serious risk of screwing your chances for survival (like being 18th level and unable to cast even a cantrip).
* Not like making attack rolls and such ... we're talking, "For you to get this ability for your character, you have to make this roll; if you don't make the roll, you can never get it" ... things like the 1E psionics system where you could be a psionic character or you couldn't based on that one roll, or like the 1E/2E method of wizards learning spells where they might never be able to learn magic missile just because of one bad roll).
** If only because the CR system expects that characters of level X are supposed to have a certain amount of power, and if one day the wild mage is pulling off 9th-level spell effects and the next day he can't manage a magic missile, it's hard to balance encounters--quite often they're a cakewalk because the wild mage is rolling well or they're a slaughter because the wild mage can't roll to save his life.
To use this material you'll also need the Wild Magic Student feat.
Wild Magic Rules
Wild surges are fluctuations in a spell caused by randomization or chaos in the source of the spell energy. These randomizations can make the spell weaker or stronger, or even cause it to have a totally different effect or backfire upon the caster.
When a spellcaster casts a spell with a wild surge, the player rolls 4d6, disregards the lowest number, and compares the result to Table 1-1: Ability Modifers and Bonus Spells in Core Rulebook I.). The result is the surge modifier. The surge modifier is added to the caster level of the spell. A spell's caster level cannot be modified below 1, although the caster level can be modified below the minimum level to cast a spell. If the modified caster level means that the spell's range cannot reach the target, the spell activates at the end point of the spell's new maximum range along the line of effect to the original target. A spell with a caster level of 0 or less does not function (as if the spellcasting had been disrupted).
Example: Marlee at 5th level spends a wild magic point to cause a wild surge in her fireball spell. She rolls 4d6 and gets 1, 1, 1, 4. Disregarding the lowest die gets her a 6, which according to Table 1-1: Ability Modifers and Bonus Spells gives her a surge modifier of -2. Adding the surge modifier to her caster level gets her a final caster level of 3 (5 + -2). Her fireball acts as if cast by a 3rd-level caster (it has a 520 ft. range and deals 3d6 fire damage).
If the surge modifier is an even number or 0, the spell may have a greater surge. The caster attempts a Will saving throw (DC 15 + spell level). Like all saving throws, the caster can voluntarily fail this saving throw. If failed, there is no greater surge. If successful, the caster rolls d% and consults the Wild Magic Greater Surge Table below. Higher results are generally more beneficial to the caster, lower results are generally less beneficial. All greater surge effects based on spells take effect at the caster's normal caster level. Any surge effect that is inappropriate for the spell (such as "Spell changes energy type" for a spell that doesn't do energy damage) means the greater surge has no effect.
Wild Magic Greater Surge Table
When gods battle, sometimes the nature of magic in the world is changed or even damaged. These damaged areas attract the interest of some mages, for these areas of raw and uncontrolled magic held the keys to the underpinnings of magic itself. By studying these damaged areas, they may find clues to unlocking even more powerful or fundamental arcane forces. These students of uncontrolled magic are wild mages. There are dabblers in this style of magic, fools who enjoy the rush of a spell surging beyond its normal bounds, but the true wild magic dismiss these people as dangerous charlatans.
Wild mages are skilled in the art of magic and the theories behind it. Many are driven individuals, intent on plumbing the depths of the well of arcane secrets. Others are exuberant experimenters, trying to expand the boundaries of the possibilites of magic. Some of both kinds go mad, and they can become very dangerous.
A majority of wild mages are wizards, with sorcerers coming in a close second. Some bards become wild mages, but the necessity for study and the disharmonics of many musical wild surges are unpleasant to most of them. A few clerics of chaotic and destructive deities multiclass as arcane spellcasters in order to learn wild magic, but this is rare because of the knowledge needed.
Wild mages usually work alone. Their spells tend to have dangerous side effects, so they rarely collect in schools or in civilized areas. Their research often makes them withdrawn and antisocial, and the quest to unearch the intricacies of wild magic makes them very competetive with each other.
Hit Die: d4.
To qualify to become a wild mage, a character must fulfill all the following criteria.
Feats: Alertness, Iron Will, Wild Magic Student, any metamagic feat.
Skills: Concentration 9 ranks, Knowledge (arcana) 9 ranks, Spellcraft 9 ranks.
Special: Must have visited an area of wild magic and cast a spell within it that suffered a wild magic effect (any effect other than the spell functioning normally).
Spellcasting: Able to cast 3rd-level arcane spells, as well as dispel magic or greater dispelling.
The wild mage's class skills (and the key ability for each skill) are Concentration (Con), Craft (Int), Knowledge (arcana) (Int), Knowledge (the planes) (Int), Profession (Wis), Scry (Int), and Spellcraft (Int).
Skill Points at Each Level: 2 + Int modifier.
Table 2: The Wild Mage Class Level Base Attack Bonus Fort Save Ref Save Will Save Special Spellcasting
1st +0 +0 +0 +2 Wild magic skill, wild magic point +1 level of existing class
2nd +1 +0 +0 +3 Wild counterspell +1 level of existing class
3rd +1 +1 +1 +3 Wild magic point +1 level of existing class
4th +2 +1 +1 +4 Modify Surge Modifier +1 +1 level of existing class
5th +2 +1 +1 +4 Wild magic point +1 level of existing class
6th +3 +2 +2 +5 Force Greater Surge +1 level of existing class
7th +3 +2 +2 +5 Wild magic point +1 level of existing class
8th +4 +2 +2 +6 Modify Surge Modifier +2 +1 level of existing class
9th +4 +3 +3 +6 Wild magic point +1 level of existing class
10th +5 +3 +3 +7 Control Greater Surge +1 level of existing class
All of the following are class features of the wild mage prestige class.
Weapon and Armor Proficiency: Wild mages gain no proficiency with any weapons, armor, or shields.
Spellcasting: A wild mage continues training in arcane magic. Thus, when a new wild mage level is gained, the character gains new spells known and spells per day as if he had also gained a level in an arcane spellcasting class he belonged to before he added the prestige class. He does not, however, gain any other benefit a character of that class would have gained (such as metamagic or item creation feats). This essentially means that he adds the level of wild mage to the level of some other arcane spellcasting class the character has, then determines spells per day and caster level accordingly.
Wild Magic Skill: At 1st level, the wild mage gains a +2 bonus to Spellcraft checks regarding known wild magic effects (including, if a wizard, checks made to inscribe a wild spell into a spellbook).
Wild Magic Point (Su): At each odd level, the wild mage gains another wild magic point.
Wild Counterspell (Su): When counterspelling, instead of using the exact spell he is trying to counter, the wild mage may spend a wild surge point and use a spell that is one or more levels higher than the target spell.
Modify Surge Modifier (Su): At 4th level, the wild mage gains better control over the wild surges he creates. He adds +1 to all of his surge modifiers. At 8th level, this increases to +2.
Force Greater Surge (Su): When the wild mage casts a spell with a wild surge, he may cause the spell to have a greater surge, even if the surge modifier is an odd number. He does not need to make a Will saving throw to cause the spell to have a greater surge.
Control Greater Surge (Su): At 10th level, the wild mage may adjust the result of a greater surge roll by one row up or down on the table. The wild mage knows what the result of either shift would be before making the choice. He can shift the result an additional step in either direction for each wild surge point he spends for this purpose.
Example: Zallan the Wiz8/Wild Mage 10 casts a heightened disintegrate on a balor. He spent a wild surge point to cause the spell to surge, and decides to force a greater surge. The greater surge d% roll is a 21-"Spell targets an ally if an enemy was the target." Not wishing to risk disintegrating one of his friends, he could automatically shift the greater surge result one row (because he is a 10th level wild mage) to "area dispel magic centered on caster" or "nothing happens, spell slot is used up." Not finding either of these options to his liking, he spends another wild surge point to bump the result one more row to the "shimmering colors/glitterdust" effect, since that won't hurt him too badly and might actually hinder the balor. The heightened disintegrate goes off normally and Zallan is surrounded by swirling colors.