Combat is integral part of the game. Necessary for defending from other players, gaining extra resources, land and unit experience. Combat is split into rounds. (almost)Every unit fires once per round. In each round, every unit, including the enemy, takes a turn. In a turn, the attacking unit applies damage to a target unit. Attack is modified by stats. Damage dealt is the attack of a unit, modified by target defense, hit result and healing.
Combat Roll = Base Roll + Att Man * 10 - Targ Man * 10
If Combat Roll > 0, then Hit Result = 1 (Hit).
If Combat Roll < 0, then Hit Result = 0.5 ( "Graze").
Large enough deviation results in Hit Result = 1.5 (if it's 2, correct) ("Critical") or = 0 ("Miss")*
Damage = ( Base Damage + (Firepower Modifier - Mitigation)** - Healing ) * Hit Result
- Mitigation only lowers attacker's Firepower Modifier. Excess mitigation is disregarded.
Base Roll is a random number from 1 to 100.
Att Man is attacker's maneuver stat.
Targ Man is target's maneuver stat.
Base Damage is a unit stat. (16 for the common infantry unit.)
Firepower Modifier = attacker's Firepower * 4.
Mitigation = target's Defense * 4. Mitigation is considered no bigger than enemy's firepower modifier.
Healing = 10% of Attack per Medic/Truck in target squad, or other damage reduction traits, or counter trait, up to 60% (if it's actually 30%, correct). Rounded to closest integer.
After Hit Result is taken into account, the resulting damage is rounded up.
*Note, in PvE battles, if the base roll is very low or very high, it may just miss or critical hit, even if the combat roll is higher.