Yeah, but the "neat" part is using the same treasures twice - once for buying Mandarin, and then the second time. I don't think that any other Dominion interaction allows for that.
Counterfeit?
Herbalist?
With Herbalist you can not use a treasure twice during the same turn.
Oh, that's what was meant. Well BM + HoP + Graverobber or Rogue also let you do this. For treasures other than HoP, Counterfeit was mentioned and that could work with BM and Graverobber/Rogue for
multiple plays of the same treasure in one turn, not just the two of buying Mandarin.
Also worth noting Mandarin doesn't have to be bought, it could be gained with e.g. Altar or Jester or Graverobber/Rogue or even Highway+IW and such
almost as good as Storeroom / Gardens.
I just played a game with Storeroom, Gardens, and P-stone. Mmmm.
One I think a lot of people miss: Gardens and Soothsayer. ~3 Soothsayers lets you simultaneously contest Gardens and Provinces in a way that can really catch your opponent off guard (they'll only be going for one, and you'll win because you can contest both)