Darkened

"An infinitude of alternate realities exist side by side. From the dawn of time, each of these alternate realities has been beyond the reach of the others. Until now. The wall separating earth and another of the realities crumbles. The fabric of existence itself unravels. Soon an army of winged creatures tears its way into our world, laying waste to the entire planet. But this is only the beginning of the human race's nightmare. A strange rot begins to infect our world, causing inorganic matter to decay at an accelerated rate. Gleaming modern skyscrapers fall to ruin in a matter of weeks. Cars become rusted hulks. Two other creatures from the alien realm, each far more powerful than the winged warriors who decimated the planet, have also slipped into our world. One exists only to kill and destroy. The other is its ancient enemy and has come to earth in a final attempt to vanquish The Dark One. Some of the surviving humans find themselves used as helpless puppets by the opposing forces. They are pawns in a larger game destined to end in a final showdown that will determine the ultimate fate of the world." – quoted from this book's product page on Amazon.com as of 2017-07-21.