[Pocus]

FORWARD, MARCH:

Not a combos per se, but something rather interesting to know:

The common behavior for troops with melee and missile weapons (ex legionaries) are to use them as infantry, and order them to hold&attack or attack closest.
It results often in the troop engaging the enemy, and firing a volley of pilum in a suboptimal manner (sometime they dont, sometime only the Last line fire, etc.)

Now use them as archers. Order your legionaries, or javelin thrower to fire. Just that, fire.
What will happen? If they have ammo and an enemy in range, they fire. Each time. Its a great improvement compared to the standard behavior.
If they dont have enemy in range, or dont have any more javelins, they move to close and engage the enemy. For archers it is somehow problematic, for legionaries, its what you want.

So try this order, you will see that you get far more pilums and javelins thrown, and they still act as infantry after.

As I said, a very small trick...