The pillars guard the entrance to a long passageway, a walk that curves round and round, almost as if it was once carved by a snake undulating through the earth, except that it is shod in good stone, and square and tall, a properly built tunnel. No doors or tunnels appear to either side, yet the way is well lit from up above. It is perhaps a mile or more into the earth before another room appears, and this is a splendid armoury, covered in all manner of glowing and gleaming weaponry, each one of pristine form and condition. It is large enough that almost any weapon or taste appears to be catered for.
[spoiler]Never said it was a charm effect. Also, there are effects such as command and control undead that explicitly affect you, so, no, not immune. I'm also fairly likely to use the ruling that intelligent undead are not immune to mind-affecting spells. After all, they aren't mindless.[/spoiler]