House of Whispers
Speak with Variks in Charon's Crossing.
Variks believes this is the perfect time for you to attack Riis-Reborn again, taking advantage of the Vex presence there. He's ready to help you and the Vanguard do so.
"Variks sees now… Europa could never be Riis-Reborn. Not truly. But the grief lingers." —Variks the Loyal