Tactics for the Swamp (Fortress).

If you play on random maps, then Swamp is stronger than Castle (arguments and debates will now begin :). I have links to reports of online battles in my signature, where there are good games played by strong players using Swamp. Read them; I think there's something to learn from them. You can also read the reports from last season here. We can argue endlessly, but you can find out what Swamp is capable of in practice by reading these reports.
Based on this statistics of games from last season on random maps, it’s hard to say that Swamp is weak :)