The morale of a unit is the probability of the unit repeating its action in battle. With a positive morale value and some luck, a unit may act twice in one round, while with poor morale, it may do nothing. (Note: Morale is often referred to as the Combat Spirit of the troops). The combat spirit of an army is modified in various ways: by the hero's "Leadership" skill, by artifacts, by visiting locations that increase (or decrease) morale, by the presence of a tavern in the city (for the garrison), by the presence of creatures in the army that increase (or decrease) combat spirit (or those of the enemy), and also: +1 if the army consists of units of the same race; -1 if the army contains undead (excluding Necropolis armies); -1 if the army consists of units of three different races; -1 for each unit of a different race after three (For example: three different races - morale -1, four -2, five -3).
The magnitude of morale (+1, +2, +3) gives the probability of repeated turns in percentage terms, respectively (4.2; 8.3; 12.5)%. Negative morale does the same, only the magnitude of the negative morale affects the skipping of turns in the same proportional relationships.
But if one player has Leadership +1, and the other has +3, then in battles it sometimes happens that the one with +1 gets a repeated turn more often. This can sometimes be very frustrating. :). Or when you have Torgrim and a resistance percentage of about 30%, and the opponent attacks three times in a row with magic, and the resistance doesn't work. The next time, it might work three times in a row. The game simply calculates the percentage of "probability," which is impossible to predict.
The priority of the first turn for two units with the same speed does not depend at all on the presence of certain spells. If two opponents, for example, have archangels with the same speed, then the one who attacked will go first. The defender will go second.