I want to open Villa, go back to my Action phase and play Necropolis, just because I can.
Better yet:
First hand: 4C, Necropolis
Play 4C, buy Villa, play Villa, play Necropolis
Buy Alms, gain Villa, hey, it's your Action phase again! (And now we know why it says "once per turn").
Play Villa, now do a little Borrowing for an extra coin.
We have $2 from Villas, $1 from Borrow, which makes it $3, let's buy Ferry and move the token to Peddler.
Due to having 3 Action cards in play, Peddler costs $2 - $2 = $0
We get 2 extra Buys from Villa aside from our regular Buy, so we have 3 Buys.
We can get 3 turn 1 Peddlers!