I am referring to the Nival scripting guide:
StartCombat("Pelt", "Nemor", 10, 37, I'm not sure what number to put here – this is where the six is replaced, nil);
Pelt – Vlad, your hero, a Necromancer.
Nemor – Deidra, the opponent's hero, a Necromancer.
10 – the number of creatures of type 31 on the opponent's side.
31 – the type of creature, it seems to be a zombie.
nil – means there are no scripts.
If Deidra's actual army is different, for example, 10 liches, this army will not enter the battle. If Deidra wins, she will have 10 liches left, although I wouldn't recommend doing this, as problems may arise. After all, your hero – Vlad – needs to win. If Deidra is not on the map, she enters the battle on the first level with standard parameters (0, 1, 3, 1) with experience equal to zero (one) and with Dark Magic + Banshee Scream. If you want the opponent's hero to have different parameters, you need to do this with scripts.