I probably have 5 rounds of the boss remain 2 digit hp like this in E2 last kill
torpedo cut in just 2 digit damage
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but anyway, just finish the E2 Hard
(first time i try gif

)
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Here is fleet that i used:
E2 P1:
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LBAS: 1 green 3 bomber for both, all aim boss
E2 P2 last kill:
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LBAS same as P1
the support expedition only for boss
resources:
start with 300k / 3000 bucket resources, this is after finish P1:

and this is after P2 (mostly wasted on final kill)

for P1, not much issue, just a few retreat run at final kill
for P2, i was using nagato mutsu ark royal mogami mikuma kamoi (escort is same as my last kill)
no issue before final kill, only 2 run fail to kill boss
start to fail kill the boss at final kill, try different equipment / shipgirl, but fast fleet and go thru sub node is much better than nagato mutsu slow fleet
maybe need hayasui for refill but i do not use my hayasui yet
-maybe tama is better in E2, i plan to keep tama at E3, i choose tatsuta, which make me have some hard time at P2 last kill
-don't use kamoi like me in E2 last kill, i only because do not want to lock any other shipgirls in E2
-it seems aquila have higher bonus in E2, but i already start E2 with ark royal
-support expedition for E2 P2 last kill: i found not much difference for normal support, maybe good if choose to go pt imp node instead of sub node
after i have some retreat even with normal support, decide to only use boss support
New shipgirl: only found the new italian dd and one ark royal
For now, need to raise some >> and digest the information of E3, seems like a lot of unlock / debuff to do in E3
Good luck for all who still stuck at last boss, and yeah, my ooi, ktkm and prinz are duplicate