Only 3 seconds below the standing record, but I'm satisfied with how I played. A future time save for this strategy would be to just skip making the hammer and get it from a setpiece instead.
surface seed: 1544781501
caves: 139446951 (downpatched feb 2024)
all seeds found by me.
timestamps:
00:00 - character select
00:08 - rabbits
01:05 - entering caves
01:32 - shadow manipulator
02:12 - mining ruins statues
04:08 - crafting ruins gear
04:26 - leaving caves
04:48 - preparing the fight
05:12 - relogging
05:56 - phase 1
06:28 - phase 2
07:16 - phase 3-4
08:25 - fight ends