Nilhogg's nose

Nilhogg's nose was a small fungus that grew in the Underdark. It was edible, but provided no nutrition. When consumed, it enhanced the sense of smell for one to four hours, improving the chance of detecting and/or identifying odors. However, under the influence of this mushroom, the consumer was also more vulnerable to the effects of smells, such as the nauseating stench of a ghast, for example.