I've been looking all over the net for an answer, but haven't been able to get it.
MtGO has sets specifically made for online play only, but because the Gatherer page doesn't really distinguish them from their paper cousins, as such they are listed as legal in Modern. Thus my confusion: is it's legality global? Can I grab an earlier copy that would have been illegal otherwise for paper?
If an example is needed, take Spike Feeder. It is listed as Modern legal, but it's real versions are all in sets that aren't modern. So...