Darkhold Castle - Artifact Chamber (guardian?)

[Mystery Man]

What would make for a nasty guardian in the Artifact Chamber in the sub-basement of Darkhold Castle? There are will be no guards there and the players are going to have to leave thru it.

 

[Silver Moon]

When I ran that scenario two years ago the Zhentarim had left a group of 30 Trow to guard that section. Trow are a race of magically created giants with feet that resemble elephants. I got them out of an old issue of Dragon magazine.