When an enemy is reduced to 0 hit points the PC responsible gets to decide whether or not the enemy dies or is simply knocked silly. Rules as written, bad guys don’t get this choice: they are always lethal. A strange inequality that doesn’t fit a setting like Eberron.

Death saving throws will work as normal. However, the PC doesn’t automatically die when a third death saving throw is failed. The enemy that last dealt damage to the PC decides whether or not the character dies or is KO’d.

KO’d Condition:

• The creature is unconscious.
• The creature cannot regain hit points, nor gain temporary hit points.
• This condition can be alleviated over the course of a short rest with another creature’s help, either by an ally’s care or an enemy’s rough-housing. A KO’d creature will wake up after a 1d4 hours naturally.

Keep in mind that KO’d PCs can still take damage from attacks and ongoing damage, though they no longer make death saving throws. A KO’d PC that reaches negative hit points equal to double their healing surge value dies.

This begets a new move action:

Drag a KO’d creature: As a move action, you may move half of your Speed, round down. You may pull an adjacent KO’d creature the same number of squares you moved.