Erelas's Curious Surge
(Alteration, Wild Magic)

Range:  0
Components:  V, S, M
Duration:  1d4 rounds + 1 round per level
Casting Time:  5
Area of Effect:  20-foot + 2-foot per level radius sphere
Saving Throw:  Special

This spell can be very complicated in combat involving numerous creatures within the area effect. All sorts of simplifications may be applied at the DM's discretion, but be consistent. The example given covers all basic possibilities.
The casting of this spell causes an unusual wild-like surge in the area. Creatures within this area have their saving throws versus other effects altered as per the following table (roll once for each saving throw to determine adjustment).

Caster						D20 Roll
Level	1	2	3	4	5	6	7	8	9	10
1	-1	-1	-1	-	-	-	-	-	-	-
2	-2	-1	-1	-1	-	-	-	-	-	-
3	-2	-2	-1	-1	-1	-	-	-	-	-
4	-3	-2	-2	-1	-1	-1	-	-	-	-
5	-3	-3	-2	-2	-1	-1	-1	-	-	-
6	-4	-3	-3	-2	-2	-1	-1	-1	-	-
7	-4	-4	-3	-3	-2	-2	-1	-1	-1	-
8	-5	-4	-4	-3	-3	-2	-2	-1	-1	-
9	-5	-5	-4	-4	-3	-3	-2	-2	-1	-
10	-6	-5	-5	-4	-4	-3	-3	-2	-1	-
11	-6	-6	-5	-5	-4	-4	-3	-2	-1	-
12	-7	-6	-6	-5	-5	-4	-3	-2	-1	-
13	-7	-7	-6	-6	-5	-4	-3	-2	-1	-
14	-8	-7	-7	-6	-5	-4	-3	-2	-1	-
15	-8	-8	-7	-6	-5	-4	-3	-2	-1	-
16+	-9	-8	-7	-6	-5	-4	-3	-2	-1	-

Caster						D20 Roll
Level	11	12	13	14	15	16	17	18	19	20
1	-	-	-	-	-	-	-	+1	+1	+1
2	-	-	-	-	-	-	+1	+1	+1	+2
3	-	-	-	-	-	+1	+1	+1	+2	+2
4	-	-	-	-	+1	+1	+1	+2	+2	+3
5	-	-	-	+1	+1	+1	+2	+2	+3	+3
6	-	-	+1	+1	+1	+2	+2	+3	+3	+4
7	-	+1	+1	+1	+2	+2	+3	+3	+4	+4
8	-	+1	+1	+2	+2	+3	+3	+4	+4	+5
9	-	+1	+2	+2	+3	+3	+4	+4	+5	+5
10	-	+1	+2	+3	+3	+4	+4	+5	+5	+6
11	-	+1	+2	+3	+4	+4	+5	+5	+6	+6
12	-	+1	+2	+3	+4	+5	+5	+6	+6	+7
13	-	+1	+2	+3	+4	+5	+6	+6	+7	+7
14	-	+1	+2	+3	+4	+5	+6	+7	+7	+8
15	-	+1	+2	+3	+4	+5	+6	+7	+8	+8
16+	-	+1	+2	+3	+4	+5	+6	+7	+8	+9

The creature may attempt a normal saving throw versus spell against this spell 50% of the time each round. In other words, there's a 50-50 chance the creature may attempt a saving throw (if so desired - this spell could benefit the creature) each round. Magic resistance, wild magic immunities or resistances, or other surge protections (such as chaos shield) negate or resist the spell for that creature for the duration of this spell (if the necessary checks are successful).
The material component of this spell is a silver piece.
An example: if Erelas, the 10th-level wizard, casts this spell in the heat of combat, every creature within a 40-foot radius sphere flips a coin. If the coin lands heads, the creature may make a saving throw to negate the effects of this spell for the first round. Every round a creature is in the area effect (including the caster), a coin is flipped for that creature (if the creature so wishes - if it opts not to make the saving throw, it is automatically affected by this spell). If the coin lands tails, the creature is not entitled to a saving throw, and is affected by this spell as per the table below. If the coin is heads, the creature makes a saving throw. If the saving throw is failed, or if the creature declines the right to a saving throw, or if no saving throw is permitted, then every time that creature needs to make any other saving throws of any kind during that round, the creature must first roll 1d20 and consults the table below to see how his saving throw is affected.
Instead of flipping each round, the first flip may be used to determine the resulting effects for the duration of the spell. For instance, if the flip lands tails, the creature is absolutely affected by this spell for its duration. If it lands heads, the creature may save against this spell every round for the spell's duration. This will greatly simplify the accounting, and reduce the number of flips required for the battle.
If a creature leaves the area effect, the creature is no longer under the influence of this spell. If a creature enters the area effect during the duration of the spell, that creature is then subjected to the flips and rolls mentioned above, again if so desired. If a creature not originally affected by the spell enters the active area effect, that creature is subject to the spell as per the example above.
Any creature with magic resistance makes the check only once, when the spell is first cast. Any creature not in the area effect, but who later enters the sphere, may make a magic resistance check. If a magic resistant creature leaves the area effect and re-enters it, it is up to the DM to decide if the creature gets another magic resistance check or not, regardless of whether it made the first one (the author suggests the creature would not, since the creature has already demonstrated its resistance to this particular spell, positive or negative).
Example continued: there's a dragon (or part of one anyway) in the area effect when Erelas casts this spell. The dragon first makes a magic resistance check. It fails. It then flips a coin. The coin lands heads, so the dragon may make a saving throw. The dragon makes its saving throw. That same round, shortly after Erelas's spell goes off, another wizard casts a lightning bolt at the dragon. The dragon makes a completely normal saving throw versus that spell, as it is not affected by Erelas's spell this round.
The next round, before any other actions, the dragon again flips a coin. It again lands heads. The dragon rolls a saving throw, but fails. Erelas casts a fireball at the dragon. The dragon rolls his magic resistance, and fails. The dragon rolls 1d20, and consults the table. He rolls a 7. The table indicates the modifier, at Erelas' level of 10, to be -3. The dragon then again rolls 1d20 for a saving throw. He rolls a 12. This would normally make it for this particular dragon, but the -3 penalty applies for this roll, which brings it down to 9. He thus fails, taking full damage from the fireball.
On the third round, the dragon flips a coin. The coin lands tails, indicating that the dragon may not make a saving throw this time. Someone casts charm monster on him, he rolls his magic resistance, and fails. He rolls a 15 on 1d20, and consults the table: +3. He rolls a saving throw: 9. The modifier is applied, bringing that 9 to 12, which is enough for the dragon to save, so he is not charmed.
On the fourth round, the dragon flips a coin, which lands heads. The dragon makes a normal saving throw (no chart check needed, as this throw is against the spell itself), and succeeds, thus not having to worry about this spell this round.

