I think this was suggested by gaswafers in one of the stickied threads in the main forum, but I couldn't find it so I'm posting it here.
Basically, instant death effects like Snuff Out will now be described as and act like "all or nothing" attacks with X Power, worded something like "100 Power attack, but misses if the damage would not be fatal."
Here are the new Power values for all sources of instant death in the game:
Incinerate: 130 Power
Expel: 130 Power
*Exterminate: 130 Power
Snuff Out: 130 Power
Hand of Light: 85 Power
Hand of Night: 85 Power
Icebreaker: 70 Power
* - As far as I remember, there is no actual way for Exterminate to appear in the game at the moment.
Edit: Adjusted the Power values to better match the previous effectiveness of the abilities back when they were based off MaxHP.