Smite evil

Once per day, a Paladin may attempt to Smite Evil with one normal melee attack.

She adds her Charisma modifier x 2 (if any) to her attack roll and deals extra damage based on the paladins level. The extra damage done is 10+(3*(level-1)). Thus, a 6th level paladin does 10+3*5 (or 25) extra damage on a successful smite. If the paladin accidentally smites a creature that is not evil, or is not in range, the smite has no effect, but the ability is still used up.

At 5th level, and at every five levels thereafter, the paladin may smite evil one additional time per rest, to a maximum of five times per day at 20th level.

Added CHA x 2: I get +4 to attack with a +2 CHA when smiting.