There's a new comic up: http://www.giantitp.com/comics/oots0894.html.
Yep, that's exactly how an illusionist would guard the Gate.
Unless it's inside that big block of unpenetrableness.
Unless it's inside that big block of unpenetrableness.
So illusion spoofs True Seeing, Detect Magic, and Locate Object?

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.