Ablative Sphere
School abjuration; Level sorcerer/wizard 3
CASTING
Casting Time 1 standard action
Components V, S, M (a crystalline sphere worth 10 gp)
EFFECT
Range personal
Target you
Duration 1 minute per level (D)
DESCRIPTION
The Garundi tenaciously protect their homes, and through the years they have perfected magic to aid them in their defense.
An immobile, crystalline, weblike globe surrounds you. When the ablative sphere winks into existence, it provides you with improved cover (see below). The barrier does not impede a spell's line of sight or effect.
The sphere is 1 inch thick per caster level, has hardness 5, and 3 hit points per inch of thickness. When an ablative sphere loses hit points, the level of cover it provides is reduced. When the ablative sphere has lost one-third of its hit points, it provides cover instead of improved cover. Once it has lost two-thirds of its hit points, it provides only partial cover. Finally, when the ablative sphere's hit points reach 0, the globe is destroyed. When an attack reduces an ablative sphere's hit points to 0, you take any remaining damage.
I am having trouble adjudicating this spell.
Do you have to choose to attack the sphere instead of the caster ?
Do you have to bring down the sphere before you can attack the caster ?
Does it provoke attacks of opportunity if you attack the sphere ?
Does it still give benefits of cover versus spells despite not impeding line of sight or effect ? and if it does, does it hamper my ray spells too ?
Does the caster provoke attacks of opportunity, does he get to make attacks of opportunity ?
It is probably easiest to imagine this not as a solid sphere, but as a sphere of crystalline webbing. Damage against the sphere causes the openings to widen and new cracks to appear until it is fully destroyed.
You do not have total cover, so enemies may target you or the sphere. However, you have a +8 to AC with the initial 'improved cover' state, so it makes sense to attack the sphere.
1) The caster and the sphere are both valid targets.
2) The sphere does not need to be taken down, but so long as it exists, the caster has bonuses to AC and reflex per the Cover rules.
3) No.
4) Cover provides bonuses to AC and Reflex. So ray attacks (and other touch and ranged touch attacks; anything with a to-hit roll) and reflex save requiring spells (fireball) will be affected by this. However, other spells that do not require a to-hit or reflex save will be unaffected (magic missile, dominate, sleep, etc) will not be affected by the globe. It will not affect spells cast by the person with the globe, much as an arrow slit does not affect the archer's ability to shoot people.
5) You cannot take AOOs against targets that have cover from you. So the caster can stand next to a fighter and spam magic missile without fear of an AOO.
The question of whether or not the cover in reciprocal (everyone else has improved cover from the caster) is uncertain. Logically they should, much as a fighter standing at the arrow slip has improved cover from the archer on the other side. However, this spell only says that it "provides you with improved cover" without mention of others.
Considering that the globe is both immobile and crystalline, I'd say that (1) the caster is basically immobile as well and (2) cover applies both ways. That said, the spell doesn't actually state the radius of the sphere, only its thickness, so that could open up some interesting interpretations that negate (1)....