Origins 4: The Omega Prologue is a story mission in the video game, "South Park: The Fractured But Whole".
Plot details follow.
There's a meeting held at the Coon Lair. After the meeting, The Coon will offer you a fourth class set. The Plantmancer and Martial Artist are added to the available options. Select your desired class to continue.
Then, you will enter a very familiar tutorial sequence. Here, you get to test out your newfound powers. Complete this section to finish the mission.
Once completed, get ready to start Heading Home.