[3.5] Making Invisible Spell less broken

[Jack_Simth]

An invisible Prismatic Wall is far better than an empowered spell of that level. Enemies won't even know it's there.

Well, they won't know it's there until it blasts them into the kumquat kingdom (violet layer, random plane shift), anyway ... and even then, they might not know what hit them.

But yes:
As a +0 spell, it works just fine on Instant Direct-damage spells (as there's almost no game effect), but less so on non-damaging spells, or on area effects.