So I'm doing an Averni campaign and I'm finding the battles really hard. The campaign map is easy due that diplomacy bonus with barbarian factions but whenever I get into a battle I get slaughtered. My early Oathsworn and Heavy Phalanx infantry can barley stand up to light spear infantry and rout fairly quickly. Sieges are a nightmare, sending wave upon wave to get slaughtered.
Any tips for battles?