Ltheb Silverfrond
Explorer
Mirage Arcana interacts with line of effect simply; It doesn't change line of effect. (At least it doesn't say so; Do the RAW get a save if interacting with the Mirage?) So if I make a mirage of a wall look like an open field, and you try to blast me because I am on the other side, your spell will hit the "invisible" wall and fail; No line of effect. You might not know theres a wall there, but the "D&D magic-physics" do.