Defeat challenging missions during Nightmare Weekend and you'll be rewarded with Rare Nightmare Mods. 

Alerts will notify you where to get 10 hard-to-find dual mods. Acquire multiple mods and quickly strengthen and upgrade your Warframe and weapons.

Be prepared, Tenno. These missions will be dangerous.

Nightmare Weekend will begin on Friday, August 23 at 12 pm EDT and end on Monday, August 26 at 12 pm EDT.