I'm contemplating a scenario for Descent that involves a Basilisk. The idea in this case is a little lizard no bigger than a rat that has a power similar to Sleep. The basilisk is pretty much a one hit kill, but it's so small it would be hard to find. It's power would work using the breath template, but be completely blocked by LOS. The key trouble with my little lizard though is how to keep it alive long enough to make the game interesting.

One way might be to use 'blip' tokens ala space crusade, that aren't resolved until you're standing next to it. Once you start looking for little beasties in the dungeon you start noticing lots, but only one of the blips is the dangerous one. Thematically though, the basilisk ought to be a rather lonely thing, and any other little beasties got snacked on while 'frozen' long ago. The only other monsters that are going to be in there are undying.

Any thoughts on how to resolve movement fairly for what amounts to an invisible creature?

Have you played Doom? They have one facet I haven't seen in Descent yet, being the grates that the spider-thingies can move through. Basically on the map you have a few tiles scattered throughout that are grates. Anyone with the Scamper ability (pretty much just the spiders) can spend 1 movement point to move from one grate to any other on the map, allowing for very fast movement (and good snipering).

-shnar