Quartz
Hero
Now, you can still die by failed death saves, of course. But that takes a minimum of 3 rounds, and usually 4-5.
I'm not sure you're right here: surely the minimum is the same round? Say the enemy hits you and you go down, and then the enemy hits you two more times. That's four death saves right there. Or three enemies hit you on the same initiative count and one downs you and the other two require two death saves apiece.