Slitherine

How many elephants does a stand represent in FOG?

That depends upon which army is being represented. A vague answer . But in Medieval times armies tended to be smaller, but still need to be represented in FoG, some eastern armies could be HUGE, but still need to be represented. The army lists I think sway things as percentage of army and importance in the army. So no definitive figure unless you can say a particular army in a particular battle, but then the points and army lists would make no difference. Check out the Historical scenarios section.

I have an order of battle for Magnesia but it is for a different set of rules. I am trying to convert it to FOG but the Elephants throw me off.

if you use the frontage from the ancient tactical manuals it works out to one elephant for every 16 files of infantry. using the 250+ infantry per base that has been mentioned in a four deep formation would result in an infantry frontage of 64 files. this would be the equivalent of 4 elephants per base. you could pack the elephants into a more dense formation of about one elephant for every four infantry files for 16 elephants per base.