Played this yesterday as the Sertorian side against a regular opponent - King Billy's 14 yo son.
Both sides exchanged missle fire and slowly manoeuvred their troops to get into a good position. Roman Ranged Fire was more telling and eventually forced the Sertorian slingers and archers from the field (2-1).
The Sertorians keep plugging away and used the cavalry to clear their side of the Baetis River to start outflanking the Roman line. (2-2)
That started a slide in fortune for the Sertorians as the Roman legion and warriors started to cut through the left of the Sertorian line like a knife through butter taking out the Lusitanian levies (Auxilia and archers)(5-2).
Sertorius saw the importance of intervention and moved his heavies into the line to hammer the Roman cohorts. Heavy losses for both sides made the game a much closer affair (5-4) and victory finally came to the Sertorians after the heavy infantry took out a Roman cohort and leader in one combat. A narrow win!