Dumathoin

The Silent Guardian
He is the Keeper of Secrets under the Mountain, Dumathoin is the god of lost knowledge, and of those that died beneath the earth.

He will not speak for any reason, his duty is not to teach, or spread any creed, his is to protect against the dangers from beneath. Some have tried to test him, challenge him to combat, sneak past his sight and find what he keeps so secret. Without warning they find themselves crushed by a hammer made of molten rock that never cools, forged by Moradin himself for his silent guardian.

Indeed it is said only Moradin can get a response out of Dumathoin, if only a nod or a gesture. This speaks lengths to Moradin's authority, and Dumathoin's lack of concern for the strength of other gods and goddesses.