I'd rather leave all the Summon Coven stuff to the Summon Coven description (like permanancy and SRD spells). Anyway, you've provided a good framework:
Occultation
Abjuration (Goat Magic)
Level: Goat 3
Components: V, S, M
Casting Time: 1 minute
Area: 10 ft. radius circle
Duration: 1 hour/level
Saving Throw: None
Spell Resistance: No
The warded area becomes difficult to perceive by divination spells such as clairaudience/clairvoyance, scry, locate object or detect spells. It also prevents location by such magic items as crystal balls. If a divination is attempted against a creature or item within the area warded by this spell, the caster of the divination must succeed on a caster level check against a DC of 11 + the caster level of the spellcaster who cast occultation or the divination fails.
The spellcaster who cast occultation does not need to make caster level checks to use divination in the spell's area of effect. Any goatling who participates in a summon coven spell to enhance an occultation is considered a "caster", and the resulting spell will not ward against that goatling's divinations.
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Then I'd modify the Spell Magnitude empowerment option to affect SLAs and area of effect. What do you think?
So you don't want to allow a caster level bonus? I think that's important, since they're using it to imprison a Demon Prince.
Hold on, are you talking about having the
Spell Magnitude option in the general-purpose Empowerment special ability to affect SLAs and area of effect?
I thought we already allowed the spell-empowerment options to affect SLAs, and I'm not in favour of adding a general purpose area-of-effect boosting option, since it's
way too open to abuse. I'd rather allow an "increase area" empowerment option in the spell.
e.g.:
Empowerment (Su): ...
Attack/Damage: ... to its next attack/damage roll (including spells,
spell-like abilities, and natural weapons).
Spell Magnitude: The next spell (or
spell-like ability) the goatling casts ...
Occultation
Abjuration (Goat Magic)
Level: Goat 3
Components: V, S, M
Casting Time: 1 minute
Area: A circle with a radius up to 5 ft. per two levels
Duration: 1 hour/level
Saving Throw: None
Spell Resistance: No
The warded area becomes difficult to perceive by divination spells such as
clairaudience/clairvoyance,
scry,
locate object or detect spells. It also prevents location by such magic items as crystal balls. If a divination is attempted against a creature or item within the area warded by this spell, the caster of the divination must succeed on a caster level check against a DC of 11 + the caster level of the spellcaster who cast
occultation or the divination fails.
The spellcaster who cast
occultation does not need to make caster level checks to use divination in the spell's area of effect. Any goatling who participates in a
summon coven spell to enhance an
occultation is considered a "caster", and the resulting spell will not ward against that goatling's divinations.
Empowerment
If a goatling uses Spell Magnitude empowerment with an
occultation spell, the empowerment's enhancement bonus to caster level applies to the spell's duration and area of effect.