Neverwinter's Strongholds are going to be basically large guild halls and one of the features is that they can be attacked. The concept is soooo cool as is, but today they've previewed the defense towers you can build within your stronghold.

If your opponents have taken a lane and are bombarding your guild hall, check to see if your guild has built a tower near the enemy siege point. If there is a tower there, it can be worthwhile to take back the supply depot behind the siege point before attacking the catapults themselves. Breaking enemy control of the lane not only prevents them from adding more ammunition to the catapults, it reactivates nearby towers. The tower near the siege point automatically attacks the catapults and any enemies trying to protect them, making it that much easier to stop the bombardment.

Strongholds are coming in September and will feature PvE and PvE combat scenarios, tons of buildings to choose from, and the ability to put buildings where you want. It's the largest map in the game so far and it's actually a really cool concept. I haven't had any hands on time with it, but from what I've seen it looks pretty boss. Towers are going to be critical, from everything explained, in PvP mode so it's pretty cool to take a look at them now.

Towers are going to attack anyone who comes near them, including siege weapons. The Archer is faster, but small splash while the Sorcerress's Tower is slower, but with a larger splash. Towers seem to be mostly focused on automatically defending chokepoints and key points on the map. While no one has had access, as far as I know, to actually play stronghold PvP, I'm sure the game will hash out which towers go where for the best setups, depending on how you build your stronghold out.

Strongholds come next month, the first part of August on the 11th while PvP comes later on in September. You can read about this preview here.