Jack London, Star Warrior

This Jack London is not the author of Call of the Wild, but a young woman telepath-warrior who has taken his name as her own, and lives by his principles of survival. And her survival is no ordinary task: she lives on an earth haunted by monsters from the stars.
The Shabba'Teth.

They came, they saw, they conquered earth. Their armies of fiendish Zimvax roved stricken Terra like armored tanks, hunting the scattered tribes of what remained of human civilization.
One hope remains.
A star has fallen from the sky. A ship has crashed upon the earth, with it the chance to defeat the evil masters of chaos who toyed with the last of humanity on its home soil.