Type: General
Source: Dragon #333
While underground, you are able to draw on the strength of the surrounding stone and extend the length of your rage.
Prerequisite: Ability to rage or frenzy, raised in an underground environment.
Benefit: While underground, your rage lasts for twice as long as it normally would. However, when above ground the duration of your rage is halved.
Normal: A barbarian's rage normally lasts for a number of rounds equal to 3 + the character's (newly improved) Constitution modifier.