Superior Two Weapon Fighting

It is still unclear whether if this is going to be introduced as a feat (especially for non-rangers), and in that case what prereq is going to be.

TWF feat prereqs;
 * Two Weapon Fighting: Dex 15 (free for Ranger 2)
 * Improved Two Weapon Fighting: Dex 17, BAB 6 (free for Ranger 6)
 * Greater Two Weapon Fighting: Dex 17, BAB11 (free for Ranger 12)
 * Superior Two Weapon Fighting: ???

Developer words on the topic



 * From Ranger: Tempest (Official Preview) by Eladrin;
 * Ranger Tempest III
 * Prerequisites: Ranger level 18, Tempest II, and any one of: Two Weapon Blocking, Two Weapon Defense, Oversized Two Weapon Fighting, or Lightning Reflexes.
 * Cost: 2 AP
 * Benefit: Your skill with two weapons is unequaled - your training has turned you into a whirling tempest of steel, granting a 10% competence bonus to dual wield attack speed, a +4 shield bonus to armor class when two weapon fighting, your penalty to hit has been reduced by 2, and you gain additional attacks when two weapon fighting.
 * The additional attacks gained at tier III are identical to what we originally had planned for (the not-in-the-game) Superior Two Weapon Fighting.