Flail Expertise is a heroic tier feat available to all player characters. A character with the Flail Expertise feat gains a feat bonus to weapon attack rolls using a flail equal to +1, or +2 at 11th level, or +3 at 21st level. Additionally, when hitting a melee weapon attack using a flail, if the attack allows sliding the target, a character with the Flail Expertise can knock the target prone instead of sliding it.[MME:23]