I can see a few mistakes:
— DrHades's turn 12 —
DrHades plays a Contraband.
... -dg- prohibits DrHades from buying Gardens.
DrHades plays a Copper and a Silver.
DrHades buys a Gold.
DrHades buys a Copper.
(DrHades reshuffles.)
Buy farmland, remodel estate into the last Garden.?
— DrHades's turn 13 —
DrHades plays 4 Coppers.
DrHades buys a Potion.
No sure about this?
— DrHades's turn 17 —
DrHades plays a Pawn.
... getting +1 buy and +$1.
DrHades plays a Copper, a Potion, and a Silver.
DrHades buys a Golem.
DrHades buys a Copper.
(DrHades draws: a Copper, a Pawn, 2 Gardens, and a Contraband.)
This should be a double Estate buy, you are never going to get to play Golem.
18P
— DrHades's turn (possessed by -dg-) —
DrHades plays a Pawn.
... getting +1 buy and +$1.
DrHades plays a Contraband.
... -dg- prohibits DrHades from buying Golems.
DrHades plays a Copper.
DrHades buys a Duchy.
... -dg- gains the Duchy.
Should veto duchy
Edit: Thanks deadlock, sorry this is wrong, man I hate possession.