I just started playing EB last week and have had a great campaign with the Casse. I read on another forum that slingers are very important, especially against other Gallic factions. In a battle 3-4 units of slingers can devastate an enemy unit very very quickly. Once you get some stripes on them they are even more deadly. They are especially good in sieges. They will decimate any unit that is guarding the gate.

Once you get some silver stripes on them they will take out Roman elite infantry no problem. Just protect them with your spears and use your chariots to do hit and run attacks on the enemy flanks. I was suprised myself. I didnt even bother with slingers until someone said i should try them. No I keep at least 4 in all my armys. :)