Umm historical allusions to people/things such as Bismark, Napolean, warsaw pact etc?
Using everyday words such as "desks" or "net" and giving them entirely new meanings using the science fiction genre?
Juxtaposition: when Ender kills the giant shows that he will not be a satisfied military leader?
I'm not sure, I've only read it before and this is just ramblings, not doing it as my Area of Study, sorry I couldn't be of more help!