Activision has announced that Call of Duty: Modern Warfare and Call of Duty: Warzone's upcoming Season Six will see Farah and Nikolai added to the game as Operators in Season Six.
Farah was one of the main protaganists in Modern Warfare's main campaign and reappears here after the story as the founder and Commander of the Urzikstani Liberation Force. She'll be available right from Tier 0 of the Season Six Battle Pass with additional skins for the character available to be unlocked through progression of said battle pass.
Call of Duty veterans will be familiar with Nikolai with the character first appearing in the original Call of Duty 4: Modern Warfare timeline, with this game's version of him being the leader of the Chimera forces under the Allegiance banner and dubbed as a "long-time friend" to ol' Mutton-Chops himself, Captain Price. You'll have to hit Tier 100 in the Battle Pass to unlock him.
As to the other stuff appearing in Season Six, Activision are remaining coy on for now, but you can watch the cinematic trailer for Farah and Nikolai's addition below. Season Six of Call of Duty: Modern Warfare and Call of Duty: Warzone lands on September 29 for the games on Xbox One, PlayStation 4 and PC.