I have asked this kind of question already concerning how to combat Romans when playing a Hellenic faction. Having searched the forum, I found no help in fighting Hayasdan, so I'm gonna start this thread in the hope of hearing some advice regarding which units and which tactics one should use if one was playing a hellenic faction and making war against Hayasdan...

And we're talking Hayadan far into the campaign, when they've conquered most of the Caucasus and have several full stacks. What does one need to defeat them and what is absolutely useless against them? :)