The web spell tells you a lot about how it interacts with creatures and with fire, but not much else. So what happens when a wizard catches some foes in a web, and then she and her allies cast other spells at the trapped creatures? How does the "many-layered mass of strong, sticky strands" affect the later spells? Let's take for granted that we correctly apply the effects of cover and entanglement, where appropriate.
Presumably the web doesn't block line of effect, unless there's 20 feet of it between you and your target, which would give it total cover. So you can fire magic missiles at trapped creatures.
But what about using a spiritual weapon against a foe 15 feet into the web? Does the web hamper the attack in any way? "Attacking a creature in a web won’t cause you to become entangled", but I take that to refer to a character standing outside the web. The spiritual weapon would have to move through the sticky strands, yet it's only the entangled creature that gets a penalty to its attack rolls and Dexterity (and probably wouldn't even get the cover bonus to its AC, as the spiritual weapon isn't more than 5 feet away from it).
To go a stage further, what about the Spell Compendium spells manyjaws and vortex of teeth? These both create force objects that fly through the air and attack foes - targeted for manyjaws, and area for vortex of teeth. Can these spell effects fly through a web with impunity, biting the creatures trapped within? Would the whirling maelstrom of the vortex damage the webbed creatures each round, while not damaging the web or being hampered by it in any way?
Your thoughts would be appreciated!
well as for spiritual weapon I would have it make STR checks at the casters bonus to avoid being entangled.
for manyjaws I would use the same as spiritual weapon, as for vortex of teeth I would rule that the flying piranhas would destroy the web that is in the area of effect as they bite and tear at it.
As far as I know web provides concealment, NOT cover, so it could never block line of effect no matter how much of it was between you and the target.
Personally as to the other effects you mentioned, I wouldn't have them be hampered at all since they are force effects and not real objects. Although having the vortex of teeth destroy the webbing in the area does make sense. After all the web does have a listed hardness and HP so if the pirahna did enough damage....
As far as I know web provides concealment, NOT cover, so it could never block line of effect no matter how much of it was between you and the target.
No, it gives cover (or total cover).
My two cents: Creatures are the only things that can get entangled in the web. Spiritual Weapon is a spell that raises all kinds of weird questions in general, unfortunately; in this case, I'd say it avoids the cover since, as you note, it will be within 5' while attacking.
For Manyjaws and Vortex of Teeth, I don't have the description in front of me, but I would apply the +2 cover bonus to Reflex saves if applicable, but they can't be entangled.
Thanks for your feedback!
While I agree with hogarth that, technically, creatures are the only things that can get entangled in a web, I'm inclined to make rulings along the lines that andrew dockery suggests. After all, the web is a physical object (while it persists), and force objects like spiritual weapons are solid - they couldn't fly through a wall, for example. The question then becomes how much they are hampered by the web.
I think, in principle, I'll require ability checks for force objects moving through webs. Extrapolating from spiritual weapon using the caster's Wisdom modifier as its attack bonus, these checks will use the caster's key ability for spellcasting. (I considered adding in a size bonus as well, but I reckon that the lesser chance of getting stuck is offset by the greater effect when stuck.) For vortex of teeth, I like the idea that the flying piranhas shred any web they come into contact with.