I am the GM, and I have questions about how illusions can be used to conceal spellcasting.
If a wizard, say, casts major image to create a fake wall to hide behind, can the wizard see through it (because the caster does not believe it)?
If so, can the hiding wizard cast a spell from behind it and not be seen (thereby masking any somatic components)? Could this be used to avoid any attacks of opportunity (because the targets do not see the casting)?
I would think it would work for spells with only somatic components, or for spell-like abilities (which have no verbal or somatic components).
More specifically, if a creature with the SLA to cast charm monster hid behind an illusory wall, could the creature cast this spell against the PCs without being detected? I understand that if it did so in plain sight that the PCs would be able to detect it, despite the lack of V or S components, right?
I want to make a fight with a lamia matriarch interesting. If prepared, she could hide behind her illusion and try to get off some charm monster spells before initiating melee combat.
Thanks!
1. The wizard (and any other disbelieving creature) can still see a "translucent outline" of the effect. Exactly how much that occludes the wizard's vision is up to the GM.
2. Assuming the GM agrees that the wizard can see through it, yes, the wizard could cast a spell and target something on the other side of the wall.
3a. See 2.
3b. If the PCs can see the caster casting the spell or spell-like ability, they'd be able to tell that a spell was cast regardless of components, but they might not know which spell was cast.