Combat

Combat Stages
For most combat engagements, the battle will begin in day combat and follow the following set of stages. Several stages will not occur unless certain conditions are met. For Event maps, a Combined Fleet mechanic has been implemented which follows a modified combat order.

For certain nodes and events, combat begins in the Night Combat stage, then proceeds to Day combat, if certain conditions are met.

Formation Selection
With 4 or more ships in a fleet, a fleet formation must be selected before combat. The selected formation affects ship damage and hit rate.

Formation Modifier

 * The surface damage modifier applies to both shelling and torpedo attacks, but does not affect Aerial Combat or Anti-Submarine attacks.
 * Diamond Formation is only selectable as a formation with 5+ ships.
 * Flagship protection is the situation where a non-flagship ship protects the flagship from being damaged by receiving the attack instead.
 * Line Ahead has the highest offensive power for surface combat. It is the default choice for encounters after the 3rd battle node to preserve firepower because of the remaining ammo penalty.
 * Double Line is generally a good formation for heavy BB/CV fleets. There is a significant accuracy increase that benefits the typically lower accuracy carriers, while BB often still have enough firepower.
 * Line Abreast is the best formation for anti-sub purposes.
 * Echelon has not been tested extensively, but it is hypothesized to be a defensive formation for submarines.

Detection

 * Fleet LOS affects Detection rate.
 * Success increases fleet accuracy and evasion.
 * Failure prevents participation of allied planes in the aerial combat phase.

Aerial Combat
Aerial Combat Stages

Fighter Combat
$$\text {Fighter Power} = \sum^\text{All slots} \text{Floor(} \sqrt{\text{Number fighters in slot}} \times \text {Plane anti-air bonus} \text{)}$$

Fighter planes, fighter-bombers (bombers with +AA stat), and seaplane bombers participate in Fighter Combat.

The allied fleet and enemy fleet's Fighter Powers are compared to determine the result of Fighter Combat:
 * EFP: Enemy Fighter Power, FP: Fighter Power. Abbreviated to save space.
 * This calculation does not take into account any anti-air weaponry equipped on ships. Carrier anti-air stat is also not considered.
 * The percentage of planes shot down applies for both sides' respective outcomes, and is calculated per slot.
 * For example, securing Air Superiority means allied planes shoot down up to 80% of enemy planes, and the enemy under Air Incapability will shoot down up to 40%.
 * As this is applied per slot, 80% of one enemy bomber group can be shot down while a second has 0% shot down.
 * Contact can be triggered by having at least 1 carrier scout plane, seaplane scout, and/or torpedo bomber equipped. It increases damage during the bombing phase depending on the accuracy bonus of the squad triggering Contact.
 * Even if allied planes secure air supremacy, planes can still be lost (up to 10%), and the subsequent anti-air defense stage can eliminate more bombers.
 * If enemy fleet launches no fighters, while the allied fleet launches any planes, the result defaults to Air Supremacy. If both sides launch no planes, then the rest of the battle is treated the same as if Air Parity was achieved.

Anti-Air Cut-In
Added in the same update as the fall event, certain equipment combinations including an Anti-Air Director or a 10cm Twin High Angle + Director can trigger an Anti-Air Cut-In. This is displayed before the fighter combat result, but does not appear to affect enemy fighter power or the resulting air superiority. Testing is still underway for determining the exact numbers applied, but the consensus is that the effectiveness scales with the AA stat.

With an AA Cut-In from a ship with high AA stat it is possible to obliterate all incoming bombers before they do any damage and even prevent opposing carriers from attacking during the shelling phase because they lack bombers. It is possible for opponents in PVP Exercises to AA Cut-In your bombers but it is not currently shown, but may disable your carriers and inflict brutal Bauxite resupply costs. Since any ship can potentially be fit for an AA Cut-In, be wary of using carriers and bombers against fleets containing high AA ships (especially Akizuki), as they may be equipped to clear the skies of bombers. Fighter planes can still be used to establish air superiority, but bombers will be at great risk. Currently no known Enemy Vessels are capable of an AA Cut-In.

Fleet Anti-air Defense
Each enemy bomber slot is assigned at random to a defending ship. Those ships then, for each assigned enemy slot, have an approximately 50% chance to shoot down enemy planes. The number of planes shot down is given by the equations below:

$$\text{Shot Down} = \text{Floor((Ship AA } + \text{Floor(Fleet Anti-air} \times \text{Formation Modifier))} \times 0.2125\text{)}$$ $$\text{Fleet Anti-air} = \text{Floor(} \sum^\text{All slots}\text{Equipment AA Bonus} \times \text{Equipment Modifier)}$$ The "Fleet Anti-Air" bonus is the sum of every equipment slot of every ship in the fleet (including the defending ship).

Equipment Modifiers

 * Any equipment that gives an anti-air bonus will contribute to shooting down enemy bombers.
 * The ship chosen to defend against bombers is not necessarily the ship targeted by that slot.
 * The ship selected to defend is not necessarily the target of the bomber. Any allied ship, including submarines, may be chosen to defend against bombers.
 * The forward sliding and machine gun animations seem to have no correlation with the calculations.
 * These calculations only apply for the allied fleet's anti-air defense; enemy fleets seem to use a different formula.

Opening Stages
The Opening Stages of combat proceed in order with the Supporting Expedition effect, the Opening Torpedo salvo, then the display of the engagement form
 * In World 5 and Event Maps, the Sortie fleet can receive a salvo of Support fire from fleets deployed on Support Expeditions. The type of supporting fire depends on the composition of the expedition fleet.
 * The Opening Torpedo Salvo is fired by Submarines over level 10, ships with the Type A Ko-hyoteki (CLTs, AVs, SS) equipped, and the Enemy Battleship Re-Class.
 * Torpedoes are fired from all ships simultaneously, and accuracy is affected by the selected Formation type.
 * The Opening stages finish with the display of the Engagement form, the orientation of the two fleets.

Engagement Form Modifier

 * Please note that all engagement forms affect both sides equally, including crossing the T ( Advantage or Disadvantage ).
 * Night battle and aerial combat are not affected by engagement forms. Torpedo salvos are affected by engagement forms.
 * Equipping a Saiun effectively makes what would have been Crossing the T (Disadvantage) become Head-on Engagement.
 * It is speculated that the Engagement form also impacts accuracy.

Day Combat

 * Day Combat consists of up to 3 phases: 1st Shelling, 2nd Shelling, Closing Torpedo
 * During the first shelling stage, the order of fire is determined by the ship's maximum range.
 * Ships are arranged in order from Very Long -> Long -> Medium -> Short range.
 * The shelling order alternates from allied ships to enemy ships if able. If two ships on the same side have the same range, the ship that attacks first from between them is chosen randomly.
 * The second shelling phase moves from the top to the bottom of the combat line.
 * CVLs and CVs must be in good or lightly damaged condition in order to participate in shelling phases, with the exception of Armored Aircraft Carriers (e.g. Taihou) who can still attack while moderately damaged.
 * The Closing Torpedo salvo is fired by all SS, DD, CL, CA, Bismarck drei, and the enemy Battleship Re-Class.
 * Torpedoes are fired from all ships simultaneously, and accuracy is affected by the selected Formation type.
 * Ships must not be moderately or heavily damaged to participate.

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 have taken more than moderate (orange) damage 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.
 * Evasion of submarines are greatly increased in regular Night Battles, so they cannot take more than scratch damage. In battles starting at night and Combined Fleet sorties, submarines do not get the Evasion boost, 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%).
 * As an exception, in nodes that begin with Night Battle and in Combined Fleet Night Battle, Formation and Engagement Form anti-sub damage modifiers apply.
 * The Engagement Form is not explicitly shown in Night Battle nodes.

Damage Calculations
Main Formula

Basic Attack Power

 * According to wikiwiki, multiple SONAR/Depth charges do not boost the ASW Bonus (i.e. 2 of each still makes the bonus 1.15)

Formation Modifier
The Base Attack Power is multiplied by the damage modifier from the selected Formation.

Engagement Modifier
The Attack power is then multiplied by the damage modifier from the Engagement Form.

Ship's Health Modifier
This modifier does not affect Aerial Combat.

Night Special Attack Modifier (Cut-In and Double Attack)
Certain Equipment setups have a chance to cause special attacks at night, causing 20-100% more damage. Detailed set ups and damage modifiers can be found in the Combat Equipment Setups below. In Night Combat, the damage modifiers from the special attack type are applied before the cap.

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 $$x$$:

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

Daytime Attack Cap often makes it important to utilize Artillery Spotting when possible to increase damage. Night Combat can be very dangerous and/or rewarding due to having a very high cap and the inclusion of torpedo to firepower for attack power calculation.

Artillery Spotting
Certain Equipment setups have a chance to cause special daytime Artillery Spotting attacks, dealing 10-50%. Detailed set ups and damage modifiers can be found in the Combat Equipment Setups below. For Artillery Spotting, the damage modifiers from the special attack type are applied after the cap.

Critical Modifier
It should be noted that the critical message always appears when damage dealt is greater than or equal to 40, regardless of whether the 150% modifier was applied or not. On the other hand, the critical message will never appear when damage dealt is less than or equal to 14, even if the 150% modifier was applied.

Contact
Contact Damage Modifier Notes
 * Contact takes place during the Aerial Combat phase. It increases bombing damage for all allied bombers.
 * When successful, a image of the squadron performing contact is shown in the opposing fleet's formation indicator, with the text "触接中".
 * Trigger conditions:
 * More air control than Air Denial
 * At least one carrier scout plane, seaplane scout, or torpedo bomber equipped.
 * Seaplane bombers, Type 3 Spotter, and Ka-type Autogyros cannot perform contact.
 * It's thought that each carrier scout plane, seaplane scout, and/or torpedo bomber slot equipped is given a chance to trigger contact. Once successful, the bonus applied is chosen at random with weighting from all eligible equipped planes.
 * Different types of planes have different trigger rates. They are roughly estimated as (if only one is equipped):
 * The damage increase depends on the +accuracy bonus of the squadron performing contact.
 * Type 2 Recon Aircraft is useful in the case that the bombing damage bonus is desired while not removing the chance for T-disadvantage, due to its high trigger rate.
 * With contact, the maximum attack power of bombing (before defense, critical and ammo) is around 180. With some luck, it's possible to sink even Ru-class Flagships (Armor = 99) in one strike without a critical.

Remaining Ammo Modifier

 * In general, two bars of will be used in Day Battle for all ships, regardless of whether they attack or not.
 * The Remaining Ammo Modifier affects all phases, including the opening Aerial Combat Phase.
 * When entering night battle, the Remaining Ammo Modifier on a vessel remains same as the previous day battle. One bar of is used for all ships in Night Battle, regardless of whether they attack or not.
 * Because most battles will consume 2 bars of ammunition each, try to engage the boss before the 5th battle, or else achieving victory becomes unlikely (but not impossible).
 * When attempting to defeat boss nodes, avoid night battles and whirlpools on the way.
 * While early maps' whirlpools decrease your resources directly, later maps will decrease either or  bars of your sorted fleet, which can be disadvantageous in long sorties.
 * Submarine-only nodes on limited-time event maps do not consume ammo in Day or Night Battle.

Combat Equipment Setups
Artillery spotting allows your ships with seaplanes to double attack and cut-in during day battle. Notes:
 * When the following conditions are all met for a ship, artillery spotting may occur.
 * Proper equipment (see below)
 * Air superiority or greater achieved in aerial combat phase
 * Thus, if aerial combat is not triggered, artillery spotting cannot occur.
 * Not in heavily damaged (大破) state
 * Ship is carrying at least 1 seaplane (i.e. slots are not all at 0 remaining).
 * Luck and sparkling do not affect the trigger chance of artillery spotting.
 * Artillery spotting cut-in attacks cannot miss, but they may inflict scratch damage instead.
 * Type 3 Shell, torpedoes and machine guns , and SONAR  and other misc. equipment like turbines do not count toward triggering artillery spotting.
 * Tables of main guns and secondary guns

Day Battle Special Attacks (Artillery Spotting)
Single Attack
 * A ship will only do a single attack if
 * Only 1 main gun is equipped and no secondary gun (e.g.).
 * No main guns are equipped (e.g. ).
 * A double attack/cut-in was not triggered by chance.
 * Damage: 100%

Double Attack
 * A ship can do a double attack during the daytime if
 * 2 or more main guns equipped (e.g. ).
 * Damage: 120 % x 2
 * Trigger chance: ~50%, affected by various factors

Cut-in Attack
 * A ship can do a cut-in attack if
 * Equipped with 1 main gun and 1-2 secondary guns (e.g. ).
 * Damage: 110 % (secondary gun cut-in)
 * equipped with 1 main gun, 1 secondary gun and 1 radar (e.g. ).
 * Triggers either secondary gun cut-in, or radar cut-in
 * Damage: 110% (sec gun CI)
 * Damage: 120% (radar CI)
 * equipped with 1 main gun, 1 secondary gun and 1 Red Shell (Armor Piercing)
 * Damage: 130 %
 * Cut-in attacks receive an accuracy bonus.
 * Trigger chance: ~50%, affected by various factors

Mixed Attack
 * A ship will have a chance to do either double attack or cut-in attack if
 * equipped with 2 main guns + 1 secondary gun (e.g. ).
 * Cut-in damage: 130 %
 * Double attack damage: 120 % x 2
 * equipped with 2 main guns + 1 Red Shell (Armor Piercing)
 * Cut-in damage: 150 %
 * Double attack damage: 120 % x 2
 * Trigger chance: ~33% each (double attack and cut-in attack), with the remainder going towards single attack.

Night Battle Special Attacks
Single Attack
 * A ship will only do a single attack if
 * only 1 main gun is equipped (e.g.).
 * no main guns are equipped (e.g. ).
 * a Double or Cut-in attack was not triggered by chance.
 * Damage: 100%

Double Attack Cut-In Attack
 * A ship will do a double attack if equipped with:
 * 2 Main Guns, no Secondary Guns, and no Torpedoes (e.g. ).
 * 1 Main Gun, 1+ Secondary Guns, and no Torpedoes (e.g. ).
 * No Main Guns and 2 or more Secondary Guns, 1 or 0 Torpedoes (e.g. ).
 * Damage: 120% x 2
 * Trigger Chance: High (??%)
 * Several types of Cut-In attacks exist
 * Cut-In (Torpedo): Two or more torpedoes equipped (e.g. ).
 * Damage 150% x 2 (simultaneous)
 * Cut-In (Mixed): 1-2 Main guns, 1 torpedo equipped (e.g. ).
 * Damage: 130% x 2 (consecutive)
 * Cut-In (Shelling): 3+ Main guns (e.g. ).
 * Damage: 200%
 * Cut-In (Shelling): 2 Main guns, 1+ Secondary guns (e.g. ).
 * Damage: 175%
 * Trigger Chance: Luck Based. See Cut-In Chance below

Note: If two attacks (simultaneous or consecutive) are made, the total damage is displayed together but the Damage Cap (and enemy Armor) is applied separately to each attack.

Anti-Sub Warfare

Any enemy submarines will force Destroyers and Light Cruisers to target them. Cut-In and Double Attacks are ignored. In normal Night Battles, ASW damage is scratch damage only. In battles starting at night, Formation Modifiers apply.

Night Double Attack Chance

Has a high and relatively consistent activation chance. Activation rate decreases with damage states, but 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:

$$(\text{0.85} \times \text{Luck} + \text{Placement Modifier} + \text{Health Modifier} + \text{Searchlight Modifier} ) \% $$

Common Setups

 * Common ship equipment setups and their purpose
 * Destroyers
 * As destroyers do not have the ability to field seaplanes, have low firepower but high torpedo stats, and few equipment slots, their use in fleets is generally to meet composition requirements. Their common setups focus on Anti-Sub Warfare, Night Torpedo, or Fleet Anti-Air Support
 * A Mixture of SONAR and Depth Charges make your destroyers effective, accurate sub killers when enemy fleets contain Submarines.
 * On destroyers with high luck (Ayanami, Shigure, Yukikaze), 2 or 3 pieces of Torpedo Equipment will often trigger a potent Torpedo Cut-In attack in Night Combat.
 * When facing maps with many enemy fleets with carriers, destroyers can provide a considerable amount of fleet AA support using 10cm High-Angle Guns or dedicated Anti-Air guns to reduce incoming bomber damage to your bigger ships.
 * Light Cruisers
 * Light Cruisers gain access to the Medium size Main guns to buff their firepower as well as seaplanes (with a few exceptions with regards to seaplanes, those being CLTs, Isuzu Kai Ni, Yuubari and both of the Tenryuu class), making Artillery Spotting setups feasible and effective against moderately armored enemy vessels.
 * For light cruisers facing enemy fleets, a setup with 2 Main guns and a Seaplane offers a potent double attack in both daytime Artillery Spotting and Night combat.
 * The special class of the Torpedo Cruisers deserves some mention here: their specialty lies in their torpedoes and should almost always be equipped to maximize their torpedo damage or accuracy with a Type A Ko-hyoteki (to enable opening torpedo strikes) and other Torpedo Equipment.
 * Heavy Cruisers
 * Heavy Cruisers see the introduction of 4 slot setups after remodeling and all of them feature the ability to launch seaplanes for artillery spotting. While they are still limited to the Medium main guns, their higher firepower and armor can make them solid combatants when Battleships are unavailable or overkill.
 * The go-to setup for most situations will be the 2 Main, 1 Secondary gun, 1 seaplane setup which provides a mixed attack pattern of double and cut-in attacks with a high activation chance during Artillery Spotting as well as a shelling cut-in during night combat.
 * When LOS requirements are important, the Secondary Gun can be replaced with a RADAR to get a Day and Night Double Attack setup.
 * Certain Event bosses take additional damage when a ship is equipped with Type 3 Shells. As heavy cruisers have access to these, a Heavy Cruiser may find swapping the secondary gun for a Type 3 Shell to be an effective pocket battleship against such targets (see Airfield Princess).
 * In the case of a battle occurring with Night Combat first, one option is to replace the seaplane with and additional gun, lose the day combat special attacks to double down on the shelling cut-in damage at night
 * Battleships
 * Battleships feature a selection of Heavy Main Guns and massive resulting firepower in addition to the potent Armor Piercing shells which can cause brutal critical hits. Setups for battleships are similar to those of heavy cruisers, with one notable addition.
 * The Armor Piercing Shells that battleships have access to allows for the highly effective 2 Main gun, AP Shell, Seaplane setup which has a more effective Artillery Spotting Cut-In, while providing better stats than secondary guns.
 * Note: Official tweets state that overuse of cannons larger than what a BB is meant for will make it "overweight" and incur a "minor" accuracy penalty. (IE: Too many 46cm or even 41cm cannons on Fast Battleships such as Kongou-class and Bismarck.) The effects haven't been noticeable enough to make any concrete statements.
 * Carriers
 * Planes. Enough Fighters to achieve Air Superiority or Supremacy, fill out with Torpedo Bombers on larger slots for preemptive bombing damage and/or Dive Bombers on smaller slots for shelling damage.
 * Torpedo Bombers and Dive Bombers are roughly equivalent to each other. While Torpedo Bombers have the advantage in the preemptive aerial bombing, their damage are dependent on number of surviving planes, making air superiority very important for them. In cases where Air Superiority is not feasible, using more Dive Bombers may prove more effective.
 * It is possible to equip Secondary Guns like the 15.5cm Triple Gun Mount or the special SCAMP to increase the carrier's range and put it higher in the Range Order shelling phase, which can be very useful for prioritizing the CV(L) damage when in a DD heavy fleet.

Full Setup List

 * What follows is an extensive list of possible equipment setups related to Artillery Spotting and Night Battle attacks.


 * Yellow: Cut-In or Double Attack Possible

Victory Conditions

 * Perfect S
 * All enemy ships sunk and no damage taken.
 * S (Victory)
 * All enemy ships sunk and no allied ships sunk.
 * A (Victory)
 * Required number of enemy ships sunk (see below) and no allied ships sunk.
 * B (Tactical Victory)
 * Sinking the enemy flagship guarantees at least a B as long as no allied ships are sunk.
 * Enemy flagship sunk, friendly ship sunk and number of friendly ships sunk < number of enemy ships sunk.
 * Damage gauge at least 2.5 times higher enemy damage 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 2.5 times as much.
 * Friendly ship sunk, damage gauge higher than enemy, but not 2.5 times as much.
 * Friendly ship sunk, enemy flagship sunk and number of friendly ships sunk ? number of enemy ships sunk. It is possible to clear maps with boss gauges (eg. 4-4, 5-3, event maps) with a C if the enemy flagship is sunk.
 * D (Defeat)
 * Enemy took less than a certain amount of damage.
 * Both sides taking 0 damage is also D.
 * If your fleet consist only 1 ship and it is reaching Heavy Damage without meeting any winning requirements, it will instantly judged as D as well.
 * 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 (Never happens in a fleet of 1).

Notes
 * The Minimum Sunk Requirement:
 * 4 ships out of a fleet of 6
 * 3 ships out of a fleet of 5
 * 2 ships out of a fleet of 4
 * 2 ships out of a fleet of 3
 * 1 ship out of a fleet of 2
 * Victory status affects the chance of getting drops and rare drops on the specified node.
 * B rank and above are necessary to obtain drops.
 * A rank and above appear to be necessary for obtaining rare drops.
 * S rank appears to have a higher chance of obtaining rare drops than A rank.
 * There appears to be a correlation between enemy fleet formations and drops, but this information is still under verification and beyond player control.