Tactical battles
Dominions is primarily a strategic game, not a tactical game. Furthermore, it is designed with an eye towards supporting a variety of multiplayer methods, including play-by-email (PBEM); and a large number of players, of which only two will be in any one battle. Therefore, the players' control of tactical battles is limited to preparation; it is up to the tactical AI to determine what individual units will do, and when.
As such, your direct control stops when the battle starts. A recording of the battle will be sent to anybody with a presence in the contested platform -- including stealthy sides not involved in the battle. In addition, battles that are initiated via remote summons are shown to the caster, regardless of whether the summons are associated with the caster or merely 'unflagged' monsters.
There is no hidden information in a battle recording. That is, all viewers get perfect information regarding unit ownership, items, spells cast, and so forth. You do not, however, get to see the actual scripts or squad assignments -- just their effects.
All battles are single-attacker versus single-defender, although either or both sides may summon monsters. Most summoned monsters are loyal to their summoner, although some will attempt to slaughter everyone on the battlefield. Battle summons are ephemeral, and will disappear after the battle.
Army setup
Army setup is quite important. For instance, it would normally make little sense to have your frail magicians in the front and your slow-moving heavy infantry in the rear. You want your vulnerable-but-important units to be fairly safe, while you want others ready to enter the fray. If you have units which are always surrounded by flames, cold, or poison, you might want to keep them separated from units which are not immune. And so forth.
Troops may be organized into squads, each of which can be placed somewhere within the army organization, and then given some basic order such as 'Hold and Attack'.
Scripting mages & commanders
As with squads, you can give your commanders a particular place to stand when planning the disposition of your army.
Commanders can command up to five squads, subject to their maximum leadership values. In addition, each may have up to five specific orders (such as "Cast Nether Darts" or "Hold"), followed by a general order (such as "Cast Spells" or "Attack").
Killer combos
If you want your magicians to use specific combinations, you should script them to ensure their use.