A group that wished to be 'ever-living' instead was cursed with 'never-dying'. Thier flesh rotted and fell fromthier bones but still they lived on. Now as skeletons they continue thier quest to remove thier curse. As skeletons they differ in that they do not need controlled or summoned. They are fully fledged NPCs with drives or ideas of thier own. Stabbing and slashing weapons would not affect them.
On the road up Dethl Mountain, you will encounter the guardian, Rustus, a goron Pyro Mage. only those who can take the heat will withstand him. to defeat him, one must use a goron's worst enemy: water