3,4

Nothing bad happens, AND the spellcaster gets 2d6 points of free, instant Recovery!

5-9

Nothing bad happens.

10

The spellcaster's skin and clothing crawl with strange energies, sparks, or other visual & aural effects for 3d6 minutes, and his eyes glow bright.  All these effects make the Hide and Move Quietly skills impossible.  Even an invisible character will be somewhat visible during this period and could be attacked normally.

11

The spellcaster is struck with a violent headache that prevents any action other than suffering (treat as Nauseated) which lasts for 2d6 rounds.  (Or a number of minutes equal to the cost of the spell that triggered the calamity, if a Fortitude check is failed - DC = 10).  Result 10 also applies.

12

The spellcaster becomes horribly nauseous and weak, (treat as Exhausted). This lasts a number of hours equal to the cost of the spell, after which the spellcaster must make a Fortitude check (DC = 15) every hour to get over the sickness.

13

The spellcaster is cursed with horrible nightmares for 3d6 days (plus a number of days equal to the spell cost).  After the first night, the spellcaster is treated as being Fatigued & Shaken.  The penalties last until the spellcaster gets a normal night's sleep.

14

Any failed spell roll that the spellcaster makes is treated as a critical failure! This lasts for 5d10 days.

15

The spellcaster's mind is temporarily damaged.  This should be treated as being Shaken, in addition, anytime the player rolls a "1" for the character, a roll must be made as if Confused.  The Shaken result takes effect immediately, and lasts one day plus one extra for every 20 points that the spell cost.  Each day thereafter, the spellcaster may make a Will check (DC = 10) to shake it off. 

16

The spellcaster has weakened the binding forces around him. His Threshold for the next 4d10 days is reduced by 2d6+5. The spellcaster is aware of a drop, but not of it's severity!  Threshold cannot be reduced below zero.  Result 10 also applies.

17

The caster loses 2d6 * 10 XP for each level of the triggering spell.

18

The spellcaster's Threshold is reduced by 4d6 + (the spell cost / caster's level); the change lasts 4d10 weeks, after which the Threshold "heals" back to normal at a rate of 1 point per day.  Threshold cannot be reduced below zero.  In addition, the spellcaster's spellcasting will be at a -2 penalty for 2d10 days. Result 10 also applies.

19

As per 17, but the caster loses 8d6 * 10 XP for each level of the triggering spell.

20

The spellcaster is aged 2d6 + 13 years, or a number of years equal to the energy cost of the triggering spell, whichever is worse.  The effect is instantaneous, with commensurate hair and nail growth.

21

Roll again (same modifier) but the result effects a companion of the spellcaster (chosen randomly).

22

As per 17, but the caster loses 32d6 * 10 XP for each level of the triggering spell.

23

The spellcaster permanently loses the ability to cast a single spell. The skill is still known, but it cannot be cast. The spellcaster must make a Will check (DC = 20).  If it is successful, he chooses which spell "dies." If not, the spell is chosen at random. On a roll of a natural "1", the GM chooses the spellcaster's most useful or favorite spell.

24

The spellcaster loses 1d3 Feats or Ability points. Choose randomly.

25

The spellcaster becomes a wandering Mana-Scar!  Spells cost double Threshold within a 2d6+3-mile radius of the spellcaster, and Recovery is HALTED in the same area. The duration, in days, equals the cost of the errant spell, plus one.  Result 10 applies for the ENTIRE duration.

26

The spellcaster's chance to cast spells is reduced by 3d4+5. The spellcaster must make a Will check (DC = 10).  If it is successful, the penalty will heal at a rate of one per day.  If not, the healing rate is one per week.

27

A plague or curse (locusts, storms, etc) descends on the region, lasting for 3d6 weeks.  No one will be able to trace this to the spellcaster (-20 to magical attempts to determine the perpetrator), but the spellcaster will know the fault is his.

28

The spell propagates out of control.  Harmful spells will affect everybody and every thing nearby, allies and enemies alike.  Beneficial spells will do likewise, but will go "over the top" and cause dangerous side effects (a healing spell might raise all the local dead, creating a horde of restless zombies out for revenge!).  Information magic will overload the spellcaster's mind (treat as Stunned until a Will check succeeds, DC = 20); Missile Spells will seem normal to the caster, but have so much punch that they drill through their target and through EVERYTHING ELSE FOR MILES beyond, and so on.  The GM should be creative and unpredictable with this result.

29

The spellcaster permanently loses the ability to cast spells.

At this level and above, the spell that causes the roll fails unless a Will check is made by the spellcaster (DC = 20 + cost of the spell / 10 + any levels of the Spellcraft skill.

30-39

As per 29, and something happens to the region the spellcaster is in.  If the result on this table was an even number, magic itself is changed (the region becomes aspected, certain spells function erratically, or some such).  If the result was odd, the change is to the physical world - the weather, birth rate, crops, or something else.  Sometimes the result is good, sometimes bad, sometimes just strange - determine the nature of the result randomly, or by fiat, or whatever is deemed most amusing to the GM.  The duration of the change is typically equal to the cost of the spell, in days, but some very dramatic effects last only a moment and some very subtle ones last indefinitely.

40+

As per 30-39, but a GLOBAL change occurs. In addition, the spellcaster must make a Fortitude check (DC = 20).  If this roll is failed, the spellcaster is consumed in a backlash of magical energy, and explodes. The explosion does damage like a grenade, doing the (spellcaster's level * 3) dice of damage, as well as killing the caster instantly!  If the Fortitude check is successful, the backlash is less dramatic; the spellcaster takes 2d6 * (caster's level) of internal burning damage, and doesn't explode.