Lightstream is here for a year already? So campaigns is good for players who were slacking on those for whatever reason, or new players like you.
I think they usually happen 1-2 month before big patch, same was with 11* 12* Falz weapons, 13* Ares, Austere etc. Then again having extra Lightstream weapon is good. Probably december raid when new hotness hits. Standard MMORPG scenario it's hard to obtain on release and more easy as time passes.
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