Combat

Effects of Ship Damage
Amount of damage on a ship will affect its performance.

Formation Modifier (Pre-Cap Modifier)
Night battle and air combat are not affected by formation choice.

Engagement Form Modifer (Pre-Cap Modifier)

 * Night battle and air combat are not affected by engagement form.
 * The engagement form attack modifier affects both your fleet and the enemy fleet.
 * This also applied for the Crossing the T (both Advantage or Disadvantage) modifier. It may be a bug or a design flaw.
 * Crossing the T (Disadvantage) can be avoided by equipping a 彩雲 Saiun (Carrier-based recon plane).

Parallel Engagement
The course of the player's fleet and the enemy fleet are the same.

Head-on Engagement
The course of the player's fleet and the enemy fleet are opposite each other.

Crossing the T
The course of the player's fleet and the enemy fleet are perpendicular to each other (that's 90 degrees, which results in a T figure). A fleet is in disadvantage if it is coming from「｜」direction, and is in advantage it is is coming from「―」direction.

(Historically, the point of this was for the「―」fleet to bring as many guns to bear on the enemy while limiting the firepower of the enemy that can only use guns mounted forward.)

Night Combat

 * Night battle damage depends on either the Firepower or Torpedo (or both!) stats for attack power, depending on the specific attack type.  Consequently, DDs, CLs, CLTs and CAs have drastically increase strength at night.
 * Any vessel at night must not have taken more than moderate (orange) damage before attacking in order to participate in night battle.>
 * Main Gun = Red guns or 10cm High-angle Gun
 * Secondary (Sub) Gun = Yellow guns / 12.7cm High-angle Gun / 8cm High-angle Gun
 * Auxiliary equipment (e.g radar, turbine, special ammunition, pure AA equipment(green), and mini-sub) will not affect the combination.

Cut-in Equipment Setups
NOTE: These are only a few examples. See the above table.

Double-attack Equipment Setups
NOTE: These are only a few examples. See the above table.

Double Attack
Two consecutive attacks at 120%. Always procs, compared to cut-ins which proc only by chance and is affected by the luck stat. (Japanese wikis confirm that Yukikaze has a greater chance of doing cut-ins than Shimakaze)

Ship's Health Modifier (Pre-Cap Modifier)
Modifier does not affect aerial attacks.

Attack Power Cap (Applies After All Pre-Cap Modifiers)
Conditions for the attack power cap to activate: [Basic attack power x Pre-cap modifiers] exceeds 150 for day battle, 300 for night battle, and 100 for anti-sub attacks. This is the attack power cap, and it's represented below by $$x$$:

$$\text {Attack Power After Caps} = x + \sqrt {\text {Pre Caps Attack Power} - x}$$

What we can draw from this is that during the day, firepower or torpedo stats above 150 have the possibility of breaking the cap immediately and thus becoming nerfed. Best to use that extra red gun on Yamato or torp on Kitakami Kai 2 on something else.

Critical Modifier
It should be noted that the critical message always appears when damage dealt is greater than or equal to 40. (If, on the other hand, the critical message appeared when the damage dealt was less than 40, then it was a critical hit.)

Remaining Ammo Modifier

 * One bar of will be used each time the ship enters shelling mode. The bar will be decreased for all ship in the fleet, regardless if they shoot or not.
 * For the Torpedo Salvo session, there will be no ammunition decrease. This also applied for the opening Torpedo Salvo.
 * This is not applied to Submarines, which their torpedo attack will also decrease their ammunition by 1 bar for each torpedo.
 * When entering night battle, the amount of ammunition on a vessel is same as after the day battle. However, on night battle, the one that have their ammunition reduced only those who fires.
 * The default ammo usage for each battle is 2 bars. In case your ship consume less than 2 bars in a battle, they'll get 2 bars decrease after the battle ends.
 * Amount of ammunition also affects aircraft carrier damage.
 * Ships which are low on fuel and/or ammo remaining have higher chance of getting heavily damaged.
 * Due to the nature that most of battles will consume 2 bars of ammunition each, on the 5th battle (nodes) in the same sortie, you'll run out of ammunition, which will ensure your loss on the next battle.
 * Make sure on every map boss battle landed on 3rd or 4th battle, since if they are on the 5th battle, your winning chance are greatly reduced.
 * To prevent the the loss of firepower while trying to reach the boss, avoid night battles and whirlpools on the way.
 * However, if you're only going for the experience and/or rare drops, do the night battle to gain the S victory, since S victory will give you more EXP and higher chance for rare drops.

Victory Conditions

 * Perfect S
 * No damage taken, all enemy ships sunk.
 * S (Victory)
 * All enemy ships sunk.
 * A (Victory)
 * No friendly ships sunk and required number of enemy ships sunk. (see below)
 * B (Tactical Victory)
 * Enemy flagship sunk.
 * If your flagship not sunk and enemy doesn't met the minimum sunk requirement (see below), you'll got B regardless how bad are you damaged if enemy's flagship sunk.
 * No damage taken, and enemy took over a certain amount of damage.
 * Damage gauge at least twice enemy damage gauge.
 * Friendly ship sunk, specified number of enemy ships sunk (see below), and damage gauge twice enemy gauge.
 * Friendly ship sunk, enemy flagship sunk, and damage gauge twice enemy gauge.
 * C (Tactical Defeat)
 * Didn't clear any of the conditions for A or B, but enemy took over a certain amount of damage.
 * Damage gauge higher than enemy gauge, but not reaching twice as much.
 * Friendly ship sunk, damage gauge higher than enemy, but not twice as much.
 * D (Defeat)
 * Enemy took less than a certain amount of damage.
 * Both sides taking 0 damage is also D.
 * Damage gauge lower than enemy gauge.
 * Friendly ship sunk, not all enemy ships sunk, and gauge lower than enemy gauge.
 * E (Defeat)
 * Over a certain number of friendly ships sunk. (see below)
 * Friendly ship sunk while not meeting any victory conditions.
 * No damage done to enemy, while taking over a certain amount.