Fey Senses

Songs of the Sidhe by David Ross

A fey’s external bond gives him a powerful intuition related to it. He instinctively recognizes threats to his bond and reacts accordingly, depending on his disposition. Most famously, this means that fey sense the unnatural aura of many undead and aberrations whenever they approach within 30 feet. Any creature whose presence makes animals nervous usually puts a fey on alert for danger. Fey’s bonds have also been suggested to impart them with their famously keen senses and innate affinity for magic. Additionally, all fey are sensitive to iron. Some suggest this is because the artifice  represented by iron is opposed to the natural magic which sustains fey. Regardless of the reason, the touch of any iron alloy (such as steel) is  unpleasant to the fey, something like touching cold liquid butter filled with biting ants. Pure iron (such as cast iron used in horseshoes) makes fey even more uncomfortable, affecting them at a distance of 5 feet. Cold iron is the worst -it affects fey at a range of 10 feet, and touching it causes mild pain. Cold iron is effective even in alloy form.

As a result, those fey who utilize metal equipment usually use alternatives to iron, such as bronze or alchemical silver. Some fey are so sensitive to iron that it can be used to repel them much like holy symbols ward off vampires.