Your opponent has 1 Province, 1 Duchy, 2 Estates, and 3 Tunnels for 17 points.
You have one action remaining. Play BV. Play Develop on Haggler, gaining BV and Trader to deck (BV on top), Silver (from BV) to discard pile.
You have one action remaining again. Play BV, drawing BV. Play BV, drawing Trader. Now you have 3 actions.
Play one Trader on Gold, gaining 6 Silvers. There are now 9 silvers left in the supply.
Play Embassy, drawing 5 Silvers. Discard 3 Tunnels, gaining Gold but using Trader to replace the Gold with Silver. There are now 6 Silvers left in the supply.
Play the other Trader on the other Gold, gaining the remaining Silvers.
You have 5 Silvers in your hand and two buys, which you use for Duchy and Tunnel. BV, Tunnel, and Silver piles are empty and you have 1 Province, 1 Duchy, 5 Tunnels for 19 points.