Assault on Atlantis - Bob Mayer - Bog

Green Beret Eric Dane and his team of Defenders embark on a dangerous quest across space and time in a desperate gamble to change the fate of the earth...
In 10,000 BC, the Shadow destroys the mighty empire of Atlantis, leaving not trace of it other than vague legend. Only a handful of survivors, priestesses and warriors survive, knowing they must pass their legacy down, so that the next time the Shadow appears, mankind will be better prepared.
Across parallel dimensions the Shadow has consumed Earth timelines, but one Timeline has repeatedly stopped it: ours.
In the past in the American west, a leader is born, who will be named Crazy Horse. Years later, he clashes with Custer at Little Big Horn in a battle that will unleash powers not apparent at the time.
In the present Eric Dane and his team have gathered the crystal skulls of mystery and legend but don't know what to do with them.
As Dane faces the Shadow's most power assault, he must use the skulls to unleash not only power from the present, but also from the past.
By the author of the bestselling Area 51, Green Beret and Time Patrol series.