Jesme throws some other arguments and thoughts around, "Well, dirt's dirt. Apparently this path is supposed to lead into the dungeons. Someone obviously intended for it to be easy enough to get down, but a lot harder to get out. The incinerator room probably was... well... an incinerator, but this room would be the last line of defense before the door with the locking mechanism."
"What does the human have in common with your summoned wolves, but both don't have in common with small rocks and dirt? Well for one, size and weight. It's a lot easier to have a trap detect pressure or force than anything else."
"Other triggers that might make sense is, as you put it, presence of living creatures, but from what I understand that's an expensive mechanism to set up. And then it might not work on undead or other strange monsters--no shortage of which have probably been kept here at one time or another. There's also a few other ideas... like detecting magic. I don't know magic, so I couldn't tell you if making those wolves appear out of nowhere is something you would detect or not, but if it is... and Errol has something magic on him, that would work as a mechanism that he and the wolves have, but not pebbles and dirt."
"But then it did only trigger twice. So there's either a fail-safe preventing the trap from going off too many times, or it was only triggered two additional times. I don't think there's any way to say which just happened."
[sblock=OOC]I think that's a fair assessment based on the trap-savvy nature of the NPC.[/sblock]