Before we start let's look which unit stats are important for combat outcome.

Health: below 100% reduces Armor and Damage stats accordingly
Loyalty: only affects probability of retreat in the end of every Combat Round
Experience: Green = -20%, Elite: +20% to Damage stat (for every attack type)


Armor: compared vs enemy attack strength (see later)
PsyDef: same as Armor but against Psy attacks

MvType: determines which attack can hit this unit (see Combat Sequence later)

Note. It also determines movement speed on various terrain, but this is outside of a combat.


Spot: detects anyone with same Camo or lower
Camo(uflage): works against Spot
Agility: reduces chances to hit this unit with every attack

Note. Every unit gets random buff for its Camo when it's created. The range of buf is from -2 to +2.

Rank. You start shooting into enemies of lower ranks first. Probably this also determines in which order your units shoot.

Attack Acc/Str list.
Most of units have a list of attacks of various strength:

Attack Type: determines attack order, count and vs which MvType it works (explained later in Combat Sequence)
Accuracy: bonus to hit, works against enemy Agility
Strength: power of the attack, works against enemy Armor (or PsyDef for Psy attack)

Note. Unit stats can be modified. For example by Sects. A green value is increased, while red value is decreased by something. This does not take into account unit Health or Agility/Accuracy bonuses of Noble/Officer.

Initial spot

At the start of the combat everyone reveals previously unspotted units. This likely happens because Spot gets penalties for distant hexes. (You may easily notice that by getting more and more reckon while you are getting closer and closer to the enemy stack on planet map). Also it's possible to initiate combat right from the Space.

To reveal a hidden unit you need to have someone with Spot equal or higher than enemy Camo.

Still unspotted units will receive +3 Agility for the rest of combat.

Combat Rounds

Land battles consist of infinite (?) number of rounds.

Note. Space battles only last for 1 round. But your space units have up to 3 movement points and you can initiate as much attacks.

In every round a number of phases initiated for every Weapon Type. The order of Weapon Types is from top to bottom on this table:


For example, for a land battle it starts from 3 phases of Unerwater/Naval attacks. Then 4 phases of Indirect attacks, then 2 phases of Air attacks and so on.

Each phase every attacking unit can perform an attack of the same type if it has such attack type (see Unit Stats). Then defenders counterattack similarly. See also Targetting.

For example, Militia Lgn doesn't have Naval attack and it cannot ever attack Underwater units (but still can attack Naval units)

To Hit chance:

Hit = 1d20 + Accuracy > 10 + Agility

Basically when Accuracy is equal to enemy Agility then to hit chance is 50%. Every additional +1 for Accuracy gets you +5% to hit chance. When enemy agility is higher then you get -5% to hit chance for every point of difference.

Note. Once a hiden unit attacks in combat it becomes revealed but still has +3 Agility bonus. However if battle is done before that happens it still remains hidden. Basically a combat is an additional option to detect some of the hidden units where you can't do that otherwise.

Routing

In the end of each Combat Round surviving units may route depending on their Loyalty.

Once hit is successfull the damage is determined.

For that the attack Strength is compared to enemy Armor (PsyDef in case of Psy attack).

The following table explains the damage dealt:


On the table we can ignore the rows. They are basically for randomization like +/- 5% .. 10%.

To understand the damage table let's look just into a few marked values.

Basically if your attack Strength is at least equal to enemy Armor then you hit it for 30 Health Damage. If your attack is lower than that, then you only deal 10 damage on successful hit. This is very big difference and the only one you must know from this table.

If your attack Strength is 2, 3 or more times higher than enemy Armor then you hit it even harder: for 45, 50 etc up to 100.

If you need to multiply your attack Strength by 3, 4 or more to break the enemy Armor then you hit it even weaker: for 4, 2 or even 1 or 0.

Note. Additionally it is worth noting that units with high armor (>50 or like that) is almost impossible to damage for more than 30 damage per 1 hit. However, Armor is reduced with Health damage. If your first hit damages someone by 30, then next hits may damage for 45 etc. This is because with reduced Health they now have less Armor (and also counterattack weaker).

Units can only target someone revealed. After full combat round everyone gets revealed eventually, but it could make a difference in the first round.

Enemy units have Rank. Your units attack everyone in the lowest rank first.

Some units like spies, nobles etc start targetting from Rank 6 and go higher.

It's still unclear to me if you have to destroy units in say Rank 2 before you start targetting units in Rank 3 or if you have more units then they may target higher Ranks earlier. Let us know if you know )

Cities increase Armor of units stationed there. x1.5 for most cities. Forts and Palace have x2 increase what makes them very good defensive positions.

Other terrain does not impact any combat.

Note. There is AGILITY.DAT file in particular which may possibly influence terrain impact. This may probably be used in the mods.

Nobles and Officers provide Accuracy and Agility bonuses to the stack. Also retreat/rout bonus. These bonuses do not stack. Noble is much better but they are precious while Officers are expendable.


If your house has Battlemaster trait then Noble also grants this Armor bonus to the stack.

When attacking on your turn you have an option to get a bonus to Accuracy or Agility:


For example, when your armors with Indirect Weapon attack Infantry with only Close Weapon you may choose Assault option to kill them before their Close phases even start.

It is possible to perform an attack of an adjacent hex even if your stack can't move there (!). This applies to Naval/Underwater units (they can attack units on coastal hexes). They can also move along rivers btw. Such attacks of adjacent hexes also apply to Mech, Crawler and Gate units. I'm not sure when it is useful though unless they attack Naval units from a coastal hex.

Regarding MvType vs Attack Types table. There is no difference between say Foot and Wheel/Treed units at all. Well, aside the fact that Foot units can't be attacked from Space. Similarly there is no difference between Indirect, Direct and Close attacks vs Foot/Wheel/Tread units. The only difference that Indirect attacks come first, then Direct, while Close is the last from them. Also Close attacks can't hit Space/Lander or Naval units, while Direct attacks can.

Psy attack is always the last in the Round. So is it anything good then? First, it can hit everything (no other attack type can do that). Second, it goes vs PsyDef instead of Armor, so in particular it's good vs armored units. The only problem is to survive till the end of Round (and better not receive much damage either).