Enigma Twins — Robin Buckallew

When the UN calls Witch Central Command and asks for their best team, naturally they call on Anikka. What begins as a simple mission to restore power to human communities in a days-long blackout quickly grows to something much more complex. When mysterious witch twins show up looking for their missing parents, Phoebe's team is on the job. The trail takes her in several directions, revealing a room under a landfill, a kidnapped witch, and eventually an old enemy who has allied with new enemies. Help comes from an unexpected source, ending in the showdown of the century...or any century.