Resonance — Dianne J. Wilson

As the enemy gains a stronghold in the underground, multitudes are recruited, marked, and repurposed. Kai must gather a band of broken, homeless kids and get back to the spiritual realm. But Negative Affinity Serum blocks his gifting. Plunged into a desperate struggle against time and Shasta, the race is on to rescue his friends and find a way back to the natural realm before Shasta deploys the multitude and turns society against Tau.