So What is a Night Spinner Anyway?
The Night Spinner has the following profile:
12/12/10 Fast, Skimmer, Tank
Twin-Linked Doomweaver: 12-72" S:6 AP: - Heavy 1, Large Blast, Barrage, Rending
Place a marker next to any unit hit. Any such units count as being in difficult and dangerous terrain the next time they move for any reason. After they have competed their next movement, remove the marker.
This weapon has several key advantages: it's twin-linked so it will usually hit something, and it's a large blast so its great against massed infantry. It's a barrage weapon so you don't need line of sight and only models actually in area terrain count as being in cover. This also means it causes pinning, which is great against non-fearless units. The rending makes it more effective against MEQs, and also able to occasionally do more damage against vehicles (Rending counts as AP2).
Making the Most of the Night Spinner
So how can you use the Night Spinner to enhance your warhost? Generally speaking, its primary targets will be infantry, so you'll have to have other elements that can open up transports. But once troops are on the ground, you can use the Night Spinner to seriously impair their mobility. The twin-linked large blast will usually hit a number of models, and S6 with Rending should kill a model or two which will force a pinning test. But even if they pass the pinning test they still count as being in difficult and dangerous terrain the next time they move. Moreover, this effect happens whenever the weapon hits, regardless of whether or not it wounds or kills anything (this includes vehicles).
The benefit here is largely psychological, but in my experience it forces your opponent to make difficult decisions. If his 10 man tactical squad has to take dangerous terrain tests in order to move he may think twice about advancing them - especially since any model in the squad could roll a 1 and die (including that pesky Powerfist sergeant). And if he decides to move them anyway he has to roll difficult terrain and lose a couple models.
With this in mind I've been using the Night Spinner to try to control my opponents' movement on the board. A single shot from this tank can cause a pinning test, a morale test (if you kill enough models), a difficult terrain test and dangerous terrain tests. That's a lot of dice rolling for your opponent, and at the very least it will force him to make difficult decisions about how to use his units. And that's always a good thing.
Have you tried out the Night Spinner? What do you think? Is this tank a good replacement for a Fire Prism? Or should they be used in concert?