I would nominate one-two punch feats like the Swordmage's Combat Casting [ When you use a melee swordmage attack power and hit an enemy, your ranged and area swordmage attack powers don’t provoke opportunity attacks until the end of your next turn. ] and Closing Advantage [ When you use a ranged or area swordmage attack power and hit an enemy, you gain a +1 bonus to attack rolls and damage rolls with melee swordmage attack powers until the end of your next turn.]
They are both too situational and don't take into account actual Swordmage power usage. Swordmages have few ranged and area attacks in the first place, and every Swordmage I've seen spams Swordburst, which gets no benefit from either feat.
