The Venum

"A Model wounded by a Weapon with this Special Rule must pass a Toughness Test at the end of each subsequent Turn or suffer an additional wound."

Any Model that suffers one or more Unsaved Wounds as a result of an attack made with a Weapon with this Special Rule must make a Toughness Test in each of the Controlling Player’s subsequent Morale Sub-Phases for the remainder of the Battle. For each failed Test, that Model immediately suffers a single automatic wound with a Damage of 1 against which no Saves or Damage Mitigation Rolls can be made.