Irontongues are reptilian bipeds with humanoid bodies and serpentine heads that have the unique ability to taste the metal that was used to inflict a wound, and then hunt down the scent of the weapon and those that have been in contact with it. They are a creation of Coritem, the god of secrets, and were created with the intention of harvesting valuable information that his information brokers could exchange for greater or more obscure secrets. Irontongues have a relative amount of autonomy, but always work to Coritem's ends in some way.
It is possible to hire an irontongue to investigate on your behalf, but the information they glean will not be divulged until they receive something deemed to be of equal or greater value, such as political secrets or arcane knowledge. Irontongues do not work for coin, and will unerringly hold their secrets, even under penalty of torture or death.