I've seen this question on a few forums, and here are my own thoughts...
In the Empire FAQ it says "Does the spell Pit of Shades affect the Steam Tank? - No" This is pretty clear cut and simple, but a lot of people are saying it's a hangover from when spells without a given strength value couldn't effect the steam tank. I think this unlikely. For starters, that line of text has survived two FAQ revisions since 8th edition, and STILL it remains. So I think it's meant to be there.
As for the explanation as to WHY it should still be there...
From a fluff point of view, Pit of Shades is a bunch of spectral hands reaching up trying to drag your soul to hell. If you don't pass an initiative test to dodge their grasping fingers, you die. Now the steam tank isn't exactly great at dodging it has to be said, but while those spectral hands may be able to grasp it easily - so what? It's a massive lump of metal! They're not exactly going to do much to stop that! They're not going to drag the steam tanks immortal soul down to a place of eternal torment... so the tank has good reason to be immune.
From a game mechanics point of view, if Pit of Shades effected the steam tank it would be devastating to it. Most spell lores have a super spell at number 6 that can really put the hurt on opponents. Purple Sun is a good example - that would, and will, annihalate a steam tank. But it's a tough spell to get off. If Pit of Shades was as strong as Purple sun (and what's more without the risk of Purple Sun of rolling a misfire) then that puts a level 5 spell as better than a level 6 - which kinda defeats the point. That's why I think Pit doesn't affectt eh steam tank - to keep it from being just TOO good a spell!
Anyway, as long as that's on the FAQ I have written backup for my point of view regardless of any arguments :oP but I'm more than happy to hear your opinions... after all, if they do change it next time they redo the FAQs you get to say "I told you so..." but only if your comment is written here first - no belatedly claiming you "thought so" ;oP
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