Unless someone rules otherwise, the Firestorm Redoubt is a legitimate choice. The model is very cool.
The rules are reasonable for it, the only real downside being that the guns are BS2, as they're automated, and you can't man them. Regardless each of those Quad lascannons is a 96" range S9 AP2 Heavy 2 Twin-Linked, Skyfire, Interceptor gun. It has to fire at the nearest flyer or flying monstrous creature, which is kind of unfortunate, although it is what it's there for.