Both sides roll 1d6 for initiative; high roll wins.
Winning side fires missiles, starts spells (and finishes spells of level 1-2)
Losing side fires missiles, starts spells (and finishes spells of level 1-2)
Both sides move
Spells that were started in 2-3 take effect; archers who didn't move and haven't been engaged in melee may fire again
Melee
Obviously, this simplified version of the full combat sequence may require some interpretation and adjudication by the referee. I suggest using the details of the full sequence to inform and assist in making such judgments. This "simple sequence" was originally posted to the Knights-n-Knaves forums by T. Foster.