Quote Originally Posted by Tzardok View Post
I'm not sure how you came up with that. A tower shield can explicitely be used to grant the wielder total cover, thereby breaking line of effect (with the special exception for targetting spells. So it can't hide you from, for example, a magic missile, but it blocks explosion type effects). And gaze attacks follow line of sight, not line of effect. Concealment defends against it, but cover not (unless it is opaque).
You can stand in the open behind a sheet of glass and look at a Medusa. Otherwise, you have to not look at a Medusa whether you are hiding behind the shield or not.

Tower shields are great for lots of things. They don't really help with gaze attacks.