Combat/Night Battle

Night Combat

 * Night battle damage depends on both the Firepower and Torpedo stats for attack power. Consequently, DDs, CLs, CLTs and CAs have drastically increased strength at night.
 * Any vessel at night must not be heavily damaged ( 大破 ) before attacking in order to participate in night battle.
 * Certain combinations of weapon equipment (Main Guns, Secondary Guns, Torpedoes) will cause Cut-In or Double Attacks at night, greatly increasing accuracy and/or firepower
 * Auxiliary equipment (e.g RADAR, SONAR, Depth Charges, Searchlights, Turbines, Special ammunition, Pure AA Equipment, Torpedo Bulges, and Midget-subs) will not affect the combination.
 * If night combat nodes are anticipated, it can be very helpful to utilize specialized night battle equipment such as Star Shells and Searchlight. Type 98 Recon Seaplane (Night Scout) is also an option.
 * All ASW damages during night battle are reduced to scratch damages. This means that submarines are impossible to kill during night, as you cannot destroy a ship with scratch damages. In battles starting at night and Combined Fleet sorties, ASW damage modifiers still apply, so they will take damage as normal.
 * Formation damage modifiers and Engagement Form damage modifiers do not apply in Night Battle (i.e. they are always 100%).
 * The animation for ships equipped with 2 different torpedoes may be different but the damage output is still the same.
 * A Prototype FaT Type 95 Oxygen Torpedo Kai + 61cm Quint (Oxygen) Torpedo Mount will show a cut-in animation of FaT+Quint+Quint and if equipped the other way around, the cut-in animation will show Quint+FaT+FaT. However, both animation produces the same damage output.

Night Battle Special Attacks
Night battle special attacks allow your ship to double attack (DA) and cut-in (CI) at night. Compared to artillery spotting, these special attacks are less demanding on equipment setups and give different bonuses. Note that it is important to realize the differences between the two types of special attack and know when to use which.

Requirements

 * Not in heavily damaged ( 大破 ) state
 * Certain equipment setups (see below)

Setups and Attack Types
Different setups have chances to trigger different modes of attack. Attack modes are ONLY determined by the prerequisites. Also, feel free to add any auxiliary equipment (AP shell, seaplane, AA gun, etc.).on the remaining slots.
 * When your set up fulfills the prerequisite for multiple attack modes, the one closer to the bottom of the list will be considered.
 * Note the night battle damage cap (300) applies after these modifiers.
 * If two simultaneous attacks are made with cutins, the total damage is displayed together but the Damage Cap (and Enemy Armor reduction) is applied separately to each attack.
 * When either DA or CI is not triggered by chance, the ship will just do a normal single attack.

Night Double Attack Chance
Has a very high (~99%) and relatively consistent activation chance (source). Activation rate is not dependent on luck. This typically results in more consistent and higher average damage than cut-in setup for ships with normal luck values.

Night Cut-in chance:
It is currently known that Night Cut-in chance is affected by the type of cut-in attack used, luck, health, flagship position, Searchlight activation, Star Shell activation, and Skilled Lookouts. Note that there is a cap for luck on cut-in chance.

Probability calculation

 * As most investigations on cut-in chance are performed with torpedo cut-ins and high-level ships as flagship, these values are most accurate for those conditions.
 * Recent data suggests level may be an important factor in determining cut-in chance, but the dependence has not been well-estimated yet. Available data suggests level 1 ships have about 5%-10% lower torpedo cut-in trigger rate than level 99 ships.
 * The formulas and values here may be incorrect because previous equations were often derived from data from ships of many different levels.
 * An alternate equation has been proposed which accounts for attacker level and target luck. Note the 50 luck cap for torpedo cut-in. However, this equation is not yet widely accepted yet.

Other Modifiers

 * Skilled Lookouts seem to give a luck-type bonus to activation chance, as the cut-in chance bonus is negligible near and above the cap. (source)
 * The exact bonus is still unclear, but the end result seems to be about 3-4% increase in cut-in chance if significantly below the cap.
 * The effect of luck over the caps is negligible.