This ability is learned with 16 skill points allocated into Ruggedness skill. The skill uses the same resistance factor as Whack, meaning that an enemy immune to instant death will not swallow their pride and vacate the battle. On top of this, the user's level is factored into the calculation, with the chance for success increasing 1% with every level gained.
Mercy is learned by putting 2 points into Ruggedness this time, and costs 2 MP to use. It functions identically otherwise.