Aaron Forsythe recalls that (R&D) knew what the future held, and we were powerless to do anything about it, and unsurprisingly, Skullclamp was banned after a few months where every deck was either running or hard countering it
It allows you to cast a card as it is being discarded for an alternate (often reduced) cost
That's good recursive removal over time
Prismari Command + Kolaghans Command + Flame of Anor I dont think Ive written a list that Prismari Command or Kolaghan's Command qualify for and not put them in the top 10
More importantly, every time you tap it for mana, youre exiling something from a graveyard
Barring mass removal a la Wrath of God, or a weird combat trick (such as Giant Growth on a blocked Mahamoti Djinn), you are not losing that Wall