Shadows and Shifters by Ryver Knight

The Queen knows who Asha is…
…and will do anything to steal her void magic.
In their last encounter in the void, Asha barely escaped the Queen’s clutches. With every moment bringing Asha closer to inevitable doom, Professor Sylvester uses his ties to the growing rebellion in Althuria to give her refuge. With Lex and Zaniyah, they work relentlessly to dismantle the Queen’s tyrannical grip over the kingdom.
But everything is going haywire.
Asha’s void magic is unreliable, a mysterious mark appears on her ankle, and her sister is missing. Even the once-safe forests now burst with danger, and creatures prowl through the night, making it nearly impossible to find Althea.
With her life hanging by a thread, Asha must confront a terrifying decision:
Does she abuse her power and wreak havoc upon the world, or face the death of the person she loves most?