if you cast a decrese sense (vision) spell how does it effect combat? If the person has -6 dice to all vision tests does it also apply to combat? I'd assume that it does.

I would work under that assumption as well given that vision modifers are indeed a pool modifier in combat and perception tests. However I would cap off such penalites at blindness. Because... well.. it doesnt really get any worse than being blind, unless your also deaf.

In Shadowrun, vision modifiers are not always combat modifiers. Good example are stealth suits and camo suits. They only give penalties for perception tests, but not for combat.

Rule of thumb: If something affects the whole environment (like lighting) then it is used in combat and perception, if somehting only affects a person, it is only used for perception. Obviously you first have to percieve something visually before you can shoot at it.

I agree with Kesslan. This spell should definately work in combat. It doesn't just make you harder to notice like a chamealeon suit, an unresisted force 6 Sight Removal spell makes the target blind in every sense of the word. I would also cap it at -6.