Okay, that's about what I figured, but I wanted to be sure! Essentially imposing his will on an area to make it appear different, but still bound to that area.

One other thing that slipped my mind powers-wise though: Merlin possesses the very godmodey power of Clairvoyance, his specific flavor of which in canon allows him to see/observe any place he wishes in the present. Aside from obviously getting permission from any players whose characters he might want to spy on, will he be able to simply just... use his clairvoyance to look around and 'explore' the tunnels without having to actually bother walking through them?