Against living creatures, each unsaved wound causes 2 wounds.
*Although worded slightly differently from other magic weapons that cause multiple wounds the Flail of Skulls works in exactly the same way - each unsaved wound inflicted on living opponents causes 2 wounds. Note that the normal flail rules also apply - the flail requires two hands to use and receives a +2 Strength bonus in the first turn of any hand-to-hand combat.