I can't watch your replay, because I dont have the exact version of the beta that you have.
If you can, attach your version too, or post as a link.
The Nightmare mode on the new map got a lot harder, it's really hard to solo it now.
If you like to build towers, would be good if you had one or 2 Glacial Towers. you can make them attack the bosses, its rly helpfull.
Flame Turret has a good damage. If your base has a narrow entrance, Peasant Launcher would be a really good option. It does splash damage, so one tower would be damaging almost all creeps, in front of the walls.
If you want more info on what towers you can do, read their specs here http://fortress-surv...ildings/towers/
I dont make towers, so I can't say much about it. Try upload the map, so we can watch the replay and give you some more accurate tips