The Exo Stranger has returned, just as the Darkness was inviting you in. Instead of warning you to turn back, she says it's time to accept what it offers. The Light is not enough to face Eramis and her dark council. If you want to defeat them, you must embrace the power of Darkness as they have.
She hands you a "Splinter of Darkness." This will allow you to wield Stasis. There are others like it, all in the hands of House Salvation. Yours is weak now, but it will strengthen as your proficiency grows.
Lastly, the Exo Stranger offers you her campsite. As you collect lessons and keepsakes, return here to reflect on your experiences.
But first, you must accept the path before you. Begin by attuning your Splinter in the monolithic Ziggurat on the icy flats ahead.