Use lots of giga and velo on the side and let the giga attack stjbor or grapple on the roof and bring rocket launchers or any thing and shoot him have some Dino like gigas magmasaurs and rock golems to deal damage while you support fire.
I have killed him four times without issue cryo pod an imprinted giga good stats 500ish damage 30000ish health. Also bring very good cold weather gear a tec canteen with hot water really helps and curry. Your biggest pain will be picking bear guts from your gigas teeth for hours.
The actual boss doesn’t look like this it’s way more impressive with lots more rock, ice spikes, and snow on it. This Dododex pic is what the taxidermy looks like, because for some reason the taxidermy looks nothing like the boss… it’s because Dododex uses taxidermy poses for the pictures if you look at them you can see what I mean. (Also explains why rubble bears have no pic yet because they kinda just explode when killed..)