Sun Tzu's "The Art of War"

Origin
"The Art of War" is a military treatese written by Chinese general Sun Tzu detailing various warfare tactics. It comes in thirteen volumes and is revolutionary in understanding the tactics used hundreds and even thousands of years ago.

Effects
When any of the scrolls are read, spectral soldiers from all eras of history appear and being to violently defend the activator. Being non-sentient, they have no distinction between threats and will attempt to wage war against any other living things in the area. When 'Killed', they fade like ink before crumpling and vanishing.

The scroll can be activated without the readers knowledge, though if they're aware of the effects then they are able to command the forces as their general.