Nephalem Altar
A Nephalem Altar is an object a player may use to change their skills and passive abilities. Altars are located in "safe" towns, and also within certain dungeons.
The Altar of Storms
The altar appeared in Beta Patch 5 in response to players switching their skills in combat. The development team wanted the skills to be accessible, but were not satisfied with skills being switched in combat, as that's rather exploitative. Hence the creation and implementation of the Nephalem Altar.
Function
Quite simply, the player must approach the altar, and either click on it, or open up their skill pane interface while in range of the altar. The altar itself does not have a wide range, so it requires close proximity to use. The altar is required in order to change skills, passive abilities, and also the skills of the selected Follower. In order to re-train the follower's skill set, the player must right-click on the follower's icon (while hired), within range of a nephalem altar, and select "Re-train" from the drop-down menu.
It is currently unknown whether or not a Nephalem Altar will be required to un-socket and re-socket Runestones, or whether runes even have a requirement for changing.
