I realize this has probably been answered before, but my searches are failing. I am looking to figure out if a character can take a 5-ft step if under an effect of hampered movement. I know the definition of 5-ft step says you cannot do it in darkness or difficult terrain, but what about other situations like under the effects of a Slow spell or in an area of poor visibility.
The slow spell looks like it reduces your actual speed to half its normal amount. I don't believe this would prevent a 5-ft step as it does not cost you 2 squares of movement for a distance of 5-ft.
The poor visibility (sidenote fog cloud? poor visibility?) says it is hampered movement and is a X2 modifier. This would mean that moving a distance of 5-ft would take 10-ft of movement. Is there a stated rule that addresses this issue either in a sourcebook or within a FAQ.