Playtesting update
Having played a few games with these variant rules, I am happy to report that no major problems were found. Below, a few house epic spells developed using these rules as a guideline, and one (zone of law) is campaign specific:
Blazing Ray
Evocation [Epic, Fire]
Level: Sorcerer/Wizard 10
Components: V, S, F
Casting Time: 1 standard action
Range: Close (25 ft. + 5 ft./2 levels)
Effect: Ray
Duration: Instantaneous
Saving Throw: None
Spell Resistance: Yes
An orange-red ray of heated air and fire springs from your hand. You must succeed on a ranged touch attack with the ray to deal damage to a target. The ray deals 1d6 points of fire damage per caster level (maximum 25d6). Further, the ray ignores 5 points of fire resistance from your target.
Focus: A sliver of solidified lava.
Bursting Fireball
Evocation [Epic, Fire]
Level: Sorcerer/Wizard 10
Components: V, S
Casting Time: 1 standard action
Range: Long (400 ft. + 40 ft./level)
Area: 20-ft.-radius spread
Duration: Instantaneous
Saving Throw: Reflex half
Spell Resistance: Yes
As fireball, except that the maximum damage is 20d6, and the fierceness of the detonation may literally blow creatures caught in the spell's area off their feet.
All creatures in the area of a bursting fireball that fail their saving throws not only take full damage but are pushed to the closest square outside the perimeter of the spell's 20-foot radius spread.
Any creature moved in this manner also takes an additional 1d6 points of damage per 10 feet moved (no additional damage if moved less than 10 feet by the effect) to a maximum of 2d6 points of damage and is knocked prone. If some obstacle prevents a blasted creature from being moved to the edge of the effect, the creature is stopped and takes 1d6 points of damage from striking the barrier (in addition to any damage taken from the distance moved before then). In any event, this movement does not provoke attacks of opportunity.
Concentrated Firebrand
Evocation [Epic, Fire]
Level: Sorcerer/Wizard 10
Components: V, S
Casting Time: 1 standard action
Range: Medium (200 ft. + 20 ft./level)
Area: One 5-ft.-radius burst/level (S)
Duration: Instantaneous
Saving Throw: Reflex half
Spell Resistance: Yes
As firebrand, except that the spell ignores 10 points of fire resistance from the creatures caught in the spell's area.
Concurrent Firebrand
Evocation [Epic, Fire]
Level: Sorcerer/Wizard 10
Components: V, S
Casting Time: 1 standard action
Range: Medium (100 ft. + 10 ft./level)
Area: One 5-ft.-radius burst/level (S)
Duration: Instantaneous
Saving Throw: Reflex half
Spell Resistance: Yes
As firebrand, except that the spell takes effect twice in the same area. Any variable characteristics or decisions you would make about the spell (including selected area), are applied to both spells, with affected creatures receiving all the effects of each spell individually (including getting two saving throws and two spell resistance checks).
Twofold Disintegrate
Transmutation [Epic]
Level: Destruction 11, Sorcerer/Wizard 10
Components: V, S, M/DF
Casting Time: 1 standard action
Range: Medium (200 ft. + 20 ft./level)
Effect: 2 rays
Duration: Instantaneous
Saving Throw: Fortitude partial (object)
Spell Resistance: Yes
As disintegrate, except that two rays are fired simultaneously. The additional ray requires a separate ranged touch attack roll to hit and deals damage as normal. It can be fired at the same target as the first ray or at a different target, but all rays must be aimed at targets within 30 feet of each other.
Zone of Law
Abjuration [Epic, Lawful]
Level: Cleric 10, Sorcerer/Wizard 10
Components: V, DF, XP (if made permanent; see text)
Casting Time: 10 minutes
Range: 10 ft.
Area: 5 ft./level-radius emanation centered on a point in space
Duration: 1 hour/level or permanent (see text)
Saving Throw: None or Will negates; see text
Spell Resistance: Yes
This powerful abjuration creates a protective bubble of lawful energy.
First, this spell enables lawful creatures within its area to cast spells normally for the duration of the spell even under the influence of magic that usually impedes spellcasting, such as spell failure due to chaotic influences.
Second, similarly to magic circle against chaos, all creatures within the area gain the effects of a protection from chaos spell, and no nonlawful summoned creatures can enter the area either. You must overcome a creature's spell resistance in order to keep it at bay (as in the third function of protection from chaos), but the deflection and resistance bonuses and the protection from mental control apply regardless of enemies' spell resistance. This effect is not cumulative with protection from chaos and vice versa.
Lastly, similarly to dictum, any nonlawful creature within or entering the area of a zone of law spell suffers the following ill effects.
HD Effect
Equal to caster level Deafened
Up to caster level -1 slowed, deafened
Up to caster level -5 Paralyzed, slowed, deafened
Up to caster level -10 Killed, paralyzed, slowed, deafened
The effects are cumulative and concurrent. No saving throw is allowed against these effects.
Deafened: The creature is deafened for 1d4 rounds.
Slowed: The creature is slowed, as by the slow spell, for 2d4 rounds.
Paralyzed: The creature is paralyzed and helpless for 1d10 minutes.
Killed: Living creatures die. Undead creatures are destroyed.
Furthermore, if you are on your home plane when you cast this spell, nonlawful extraplanar creatures within or entering the area are instantly banished back to their home planes. Creatures so banished cannot return for at least 24 hours. The banishment effect allows a Will save (at a -4 penalty) to negate.
Nonlawful creatures whose HD exceed your caster level are unaffected by zone of law.
This spell may be made permanent by expending 5,000 XP.
XP Cost: 5,000 XP if made permanent.
Andargor