User blog:Hayashi H/Anti-BWS Fleets

Introduction
The purpose of this post is to attempt to create a fleet setup that would have the least possible chances of being taihaed by a BWS positioned in a pre-boss node. WARNING: HEAVY MATHS INVOLVEMENT

Assumptions
Everything else below this is based on the stats released through the UI/datamining of 's squadrons, and can be assumed to be correct by default. However, if any of the three assumptions above this are wrong, the conclusions will change respectively. All ship calculations are done with their final forms.
 * 1) >100% hp hit = 16.7% taiha on crit (20-50% HP, taiha value = 25%). This affects the chance of taiha after a ship is hit for more than its maximum HP.
 * 2) Armour value rolls with equal chances of any value between 2/3 and 4/3 of the base armour stat. This affects the range of damage allowed, which affects all taiha chances calculated.
 * 3) The crit chance is 10%. This affects the 'aggregate taiha rate' values only; the individual values of crit and non-crit are not affected.
 * 4) Parallel engagement is assumed for all the following cases, even though the firepower difference from the calculated value will not exceed 3, so any change here should be relatively small. The player will be assumed to use a Saiun such that Red T never occurs.

Calculations for various ships
Shelling A ttack = 55 + 1.5(16+16+40) + 2.0(15) = 193 attack (156 attack in parallel, 154 attack in head on, 159 attack in Green T). The value of parallel will be used as it is the most common engagement form. This affects all values.

Musashi
Musashi roll 79-158 armor, 97 hp (64 EVA), taihas at 23 HP

Noncrit 156 attack <83 armor roll = 4.6% taiha from full HP Rest: Anything from scratch to chuuha

Crit 234 attack 137+ armor roll = 97+ damage = 26.6% chance * 16.7% = 4.4% taiha 161 armor, so every roll type will result in taiha Taiha chance = 73.4% chance + 4.4% chance = 77.8%

Aggregate taiha rate assuming 10% critrate = 11.9%, 64 EVA.

Hiei
Hiei roll 63-126 armor, 83 hp (72 EVA), taihas at 20 HP

Noncrit 156 <73 armor roll = 15.9% chance * 16.7% = 2.7% taiha <93 armor roll = 31.7% chance taiha Minimum damage taken = 30 = shouha. Taiha chance = 2.7+31.7 = 34.4%

Crit 234 attack 100% exceeds HP limit, taiha rate = 16.7%.

Aggregate taiha rate assuming 10% critrate = 32.7%, 72 EVA.

Haguro (and most CAs, and everything lighter)
Haguro roll 48-97 armor, 57 hp (84 EVA), taihas at 14 HP

Noncrit 156 attack Maximum armor roll = takes 97 damage, so all rolls will deal >100% HP. Taiha rate = 16.7% regardless of crit or not, 84 EVA.

Aggregate taiha rate = 16.7%, 84 EVA

Nagato
Nagato roll 65-130 armor, 90 hp (69 EVA), taihas at 22 HP

Noncrit 156 <66 armor roll = 3% chance * 16.7% = 0.5% <88 armor roll = 33.8% chance Minimum damage taken = 26 = shouha. Taiha chance = 0.5%+33.8% = 34.3%

Crit 234 attack 100% exceeds HP limit, taiha rate = 16.7%

Aggregate taiha rate assuming 10% critrate = 32.6%, 69 EVA.

Fusou
Fusou roll 60-120 armor, 77 hp (69 EVA), taihas at 19 HP

Noncrit 156 <79 armor roll = 31.7% chance * 16.7% = 5.3% <98 armor roll = 31.7% chance Minimum damage taken = 36 = shouha. Taiha chance = 5.3%+31.7% = 37%

Crit 234 attack 100% exceeds HP limit, taiha rate = 16.7%

Aggregate taiha rate assuming 10% critrate = 35.0%, 69 EVA.

Final Comparison
Aggregate taiha rates: Musashi 11.9%, 64 EVA. Hiei 32.7%, 72 EVA. Haguro 16.7%, 84 EVA. Nagato 32.6%, 69 EVA. Fusou 35.0%, 69 EVA.

Suggested Conclusions (this part is opinion, not math, so reject at will)

 * 1) Don't sortie large numbers of non-Yamasushi battleships against  as they will have a disproportionately large chance of taiha. If you must have 1 to create the double shelling phase at boss node, have ONE. If preboss nodes have no enemy BBs, have BWS and the final boss node has something that will already trigger a double shelling phase (like a BB, Hime or Oni), take zero battleships so the BWS gets to shell only once. Yamasushi may fare better against early-node BWS if all ships' evasion are at soft cap, while in late nodes where fuel reduces evasion further, it is highly likely the CAs' higher evasion will result in them not being hit by the BWS at all.
 * 2) Sortie as few ships lighter than CAs as possible, as all of them have the same taiha chance - but the CAs have the highest chance of chuuha/sinking  before it even launches.
 * 3) Bring Maya, Akizuki or Teruzuki, and obtain Air Supremacy as far as possible. Denying BWS contact reduces the chance of it taiha-ing ships in initial airstrike, and Air Supremacy in addition to AACI has the potential of entirely eliminating its bombers so it never enters the shelling phase.