I believe that they were called 'Nightfall' missions, with additional challenges and enemies scaled up.
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Those are for the cooperative Strike missions, not the Story missions.
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Actually, PotatoBacon is correct there are nightfall story missions n strikes, daily n weekly.
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Okay, now you're confusing me. What you mean, "Daily & Weekly"?
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http://youtu.be/oFRQlCX3Ygs