Ironically describes the main villain of SWTOR: the Sith Emperor, Darth Vitiate. Born the bastard son of Lord Dramath, from childhood he was marked as especially powerful in the Dark Side even for Sith Purebloods. By the time he was 10, without any formal training, he was powerful enough to simply overpower Lord Dramath, and to impress the reigning Dark Lord of the Sith Marka Ragnos. Not to mention devious enough to avoid drawing the attention of other Sith Lords, or even the Jedi and the Republic towards the end of the Great Hyperspace War. He also ultimately became the Sith closest to ever achieve complete immortality.
And ultimately subverted in the end, with the PCs - even the Imperial characters post-Shadow of Revan expansion - turning against him and finally destroying him once and for all. All of whom started out small, and struggled to become the heroes (or anti-heroes) they eventually became.
Seconded; this especially annoys me, since it's as easy as watching a documentary or opening a history book to look up proper battle tactics. Even simple ones like double-envelopment, or a Cannae-style ambush.