Invisible Spell and Conjuration (Creation)[3.5]

[Shadowleaf]

How would you throw that on characters?


DM: You see the hall. You can hear guards talking but cannot see them.
Player1: Ghosts! I turn undead!
DM: It does nothing.
Player2: I cast See Invisible.
DM: It does nothing.
Player3: Must be a Magic Mouth spell. Let's ignore it.
DM: Suddenly, rays of fire come forth down the hall. What are your reflex saves?

Uhm. I think you misunderstand. An Invisible Solid Fog will be invisible, therefore everyone would normally be able to see through it.
A person with True Sight/See Invis., however, would negate the Invisible part of the Solid Fog, and would be able to see the fog.
It's great for, say, a Rogue. He casts Invisible Solid Fog, hides, and hopes the Wizard activates True Sight