Morph Detector (3.5e Feat)
From D&D Wiki
Morph Detector [Special]
Spot and find creatures hidden.
Prerequisite: Wis 13, must be able to change shape in one of the following five ways: change shape supernatural ability, shapechanger subtype, polymorph as a spell-like ability, able to cast the polymorph spell, wild shape or similar class feature
Benefit: Your senses become sharp, giving you blindsight. Any creature within 10ft. of you is immediately detected.
Special: This feat gives a bonus 10 feet to the range of blindsight if you already had one. You can take this feat up to 3 times. Additional Morph Detector gives an additional 10 feet to the range. If you cast the polymorph spell, has polymorph as a spell-like ability usable less often than at will, or has the wild shape class feature, then this feat loses function when you cannot use them.