Umber hulk

From NWNWiki

Umber hulks are subterranean monsters that look like a cross between a great ape and a beetle. They leave behind a wake of destruction where ever they go.

Umber Hulks possess an ability of Tremor Sense

A creature with tremorsense automatically senses the location of anything that is in contact with the ground and within range. Aquatic creatures with tremorsense can also sense the location of creatures moving through water.

If no straight path exists through the ground from the creature to those that it’s sensing, then the range defines the maximum distance of the shortest indirect path. It must itself be in contact with the ground, and the creatures must be moving.

As long as the other creatures are taking physical actions, including casting spells with somatic components, they’re considered moving; they don’t have to move from place to place for a creature with tremorsense to detect them.

Technically in NWN it allows you to "see" hiding Shadow Dancers and Rogues, but it should not be RolePlayed as exact "seeing", rather - Sensing. Meaning, a shapeshifted PC can not discern the features of the creature he sensed, being his race, skin colour etc.