Ive always though Mage Staff was one of the most underrated cards in the game.
If the Dwarf Warlord puts a Piercing Rune on one its flexibility is comical. Reach, Etherial, AND 1 Pierce for 6 mana. Even at triple spell cost its a great deal.
When playing with promos, Critical Strike makes it even Crazier with 3 Pierce/Reach/Etherial. Quite a beatstick in the hands of a Battle Skill mage at that point.