Stronghold assault seems to be the one expansion that isn't getting as much flak as Formations or Escalation. It isn't game breaking, but has some particularly hilarious options for you to use in your army. Today, I want to talk about the Escape Hatch upgrade available to buildings.
First off, it's pretty cheap. Rocking in at 25 points, you are getting yourself a great upgrade. How the escape hatch works is fairly simple. When you first occupy a building, you may place an appropriate "marker" within 12" of the building to indicate a secondary access point. This marker then stays there the entire game - giving you some serious movement flexibility. Remember that you do not place the hatch until their is an occupying unit, which subsequently happens in your own deployment phase.
Defence
The most obvious use of this upgrade is for Objective Denial. For example, using the new combined fortification rules, I decide to bring two Bastions and upgrade both with escape hatches. I place one on either side of my board edge, with only the lip of the bastion inside my deployment zone. Like this:
The circles indicate the 12" zone that you can place an escape hatch in (dodgy drawing, but you get the point).
So, I've deployed my two bastions like the picture above. This then allows me to place my objectives, preferably, within one of these zones. This means that I can have a contingency plan for securing objectives. Late game, I can pop out and score very easily.
Offence
Of course, you can do the same to your opponent. By placing the bastions in this fashion, it will force my opponent to funnel their objectives towards the center of their deployment zone. If they haven't picked up on this, and end up placing an objective "near" your 12" bubble zone, when it comes to your deployment phase, you can put the escape hatch wherever you want. Get it as close as possible to your opponents objectives so you can apply pressure as early as you can.
Pretty much any unit that can go fast AFTER the movement phase (you're still limited by the 6" disembark - which is nothing to put down). Slannesh units is another good one.
Of course, you can use this offensively to. I'll use a very basic example. Platoon command squad, all with flamers. Very cheap unit and is very effective - if used right. The main downfall of this unit is it's range. Usually, you can't get them close enough before being killed (coming out of a Vendetta is a good alternative though). So, slingshot them out of the Bastion! You can, effectively, get them to move 20-22" in the first turn (4" overlap of bastion + 12" hatch + 6" move) by using the escape hatch. If that doesn't get your flamer templates in range then I don't know what will.
Also, Zombies can use it. Continously load 20 zombies at a time into the buildings and you are slingshotting them 3 phases worth of movement and running in a single go! Hilarious. We love zombies.
Can you guys think of any other units that can use the slingshot to full advantage?