Void Traces are primarily obtained by collecting Reactant, which occasionally drops from Corrupted enemies (including those who turn Corrupted during the mission) provided there is a Void Fissure present. Reactant is collected to crack open a Void Relic, but Reactant will drop regardless if the player has a Void Relic equipped or not. As of Update: The Silver Grove 3, Void Traces can also be obtained from Void Alert missions.