What about a rabid rat that periodically/passively sends out poisonous dust, spits an arc in front of it, and lashes with great intent out w/ its limbs and tail? It could be i've never been sleeping in a box that's out of the way in the overworld vampire BATS! by having bits of vandalism(mouse tracks and gnaw marks) in the previous area. Seeing that the Valley of Repose is a sidewalk, a mutated mouse seems the right size. But is mouse-phobia a problem?