Suffocation

When a creature's body is deprived of oxygen, its brain starts shutting off. That's generally considered bad. If you can't breathe, but you're not doing anything physically taxing, such as actively fighting in combat, you can hold your breath one minute for each point of Endurance you possess. After this, you quickly black out and asphyxiate. You fight Stamina Drain so long as you go without air. The only way to remove these Knockout Track penalties is to regain the ability to breathe. Spells, items, and skill checks which remove Knockout Track penalties cannot help a creature having an asthma attack or choking on smoke from a house fire.

The suffocating condition (see below) causes Stamina Drain (DL 15; +1 every round; lethal). The lack of oxygen to the brain pulls a creature into a permanent slumber. Once you fail a fifth check and reach stage 5 on the Knockout Track, you fall comatose. If you can't take in a breath and you fail a subsequent check, you turn an odd shade of blue and die, grasping at your throat, probably.