Here is a Fun one.
Flyer Zooms, can move 18" - 36" and fire 4 weapons
Flyer can Skyfire or shoot at ground targets
Skyfire allows you to shoot at Flyers with normal BS, but unless you have Interceptor, you can only Snap Fire at Ground Units
Snapfire requirs BS1 and no blast, template, salvo, etc...
Machine Spirit allows you to fire one additional weapon than you normally could, and at a different target unit, and with full Ballistic Skill (assuming you didn't go flat out or use smoke)
What if you elected to "SkyFire" this turn with your BA Stormraven... and you shoot 4 weapons at a flyer (Two Blood Strikes, Lascannons, Multi-Melta). Can you have Machine Spirit(MS) use a 5th weapon to target a ground unit, and would it be at normal BS (Hurricane Bolters)?