Using the Nomad Camp/ Watchtower&Hamlet opening I can empty 3 piles and buy a single Province on Turn 4. I can't find a way to make it work on Turn 3 yet.
1. [Draw: CCCCE] Buy NomadCamp(4)
2. [Draw: NcCCCE] Play NomadCamp, Buy Watchtower(3), Hamlet(2)
3. [Draw: E…]
-shuffle-
3. [Draw: …HWtNcC] Play Hamlet, Draw: C, Discard CE, Play NomadCamp, Play Watchtower, Draw: CCCCC, Buy Procession(4), Buy Ironworks(4)
4. [Draw: EE…]
-shuffle-
4. [Draw: …IwWtPr] Play Procession, Play Ironworks1, Gain Procession, Reveal Watchtower, Topdeck Procession, Play Ironworks2, Gain Ironworks, Reveal Watchtower, Topdeck Ironworks, Trash Ironworks(Pr), Gain Cultist, Reveal Watchtower, Trash Cultist, Draw: IwPrX; (repeat Until Iw, Pr, Cu are empty, Buy VP)