Nothing stops TGT! The best way is purple site with immunity. Just keep your EC's safe and always have a few down. But even with the protector lost soul you have to have Blue Tassels up for Women as Snares. This card is waaaayyyyy overpowered and will be in at least one, but probably two, of the top three decks. House of Rimmon is probably the best defensive fortress with Syrians due to protection from capture and discard.
Assyrian Camp also protects from Discard and Capture, and against Conversion as well (no HG). That's a paricularly depressing thought, since two of my Syrians were converted with HG with House of Rimmon in my territory...
I didn't think that TGT would be that good against a well-built single color defense, but after losing three games against TGT decks in the past few days, I am inclined to think differently. Though honestly, TGT never really stopped me from blocking, it just forced me to think carefully about when to make my first Rescue Attempt. I may have done better if my defense had set up more quickly, so I could attack earlier.