Is it just me or is this card really good right now?
Kills equiped Batterskull guy, Emrakul, Progen, Tombstalker, Goyf & Knight most of the time.

Is Retribution underplayed for any reason other than it's White?

Do you expect to see Retribution more in SBs and top 16s soon?

What decks should be SBing Retribution right now?

A quick search shows all of 2 SCG top 16 decks ran SB Retribution in the last year both of which ran it as a wish target for 4 color Loam.