You are considered "dying" when your hit points are 0 or lower, and you die immediately if your negative hit point value is the same as your positive bloodied value.Death Saving Throw: When you are dying, you need to make a saving throw at the end of your turn each round. The result of your saving throw determines how close you are to death.
- Lower than 10: You slip one step closer to death. If you get this result three times before you take a rest, you die.
- 10-19: No change.
- 20 or higher: Spend a healing surge. When you do so, you are considered to have 0 hit points, and then your healing surge restores hit points as normal. You are no longer dying, and you are conscious but still prone. If you roll 20 or higher but have no healing surges left, your condition doesn't change.
It looks like it's on a failed save. So, unless the damage that brought you below 0 HP was enough to equal your surge value, you're still going to get your 3 failed death saving throws in (assuming the catoblepas doesn't go for the coup de gras).Sounds to me like the Catoblepas kills a dying enemy in 2 rounds no matter what, as long as that enemy is within the aura. That's pretty nasty. Unless the damage happens on a failed save, which while still nasty, is a bit less so.