ASH stands for Assassins, Spies, and Hitmen. Every book included in the promo features an assassin, spy, or hitman character in some way.
There are no download links right now, but they will be added on August 6th. In the meantime, feel free to browse the book descriptions on the page to think about which books you want to read for free. Every book listed will be available as a free e-book download on Instafreebie from August 6th-12th, and more books may be added between now and then, so check back often.