you could also just get some good food and use a mace, which he is weak too.

i guess you could also glitch yourself into an undestructable tree, and just build pikes. takes 1,5 hours to kill him that way, but yes, it works.

My version is better and quicker. Cool though

good'ol face 2 face combat - 1 man, 1 shield, 1 mace and 1 bonemass
beat him up in no time
better than cheesing yourself or take 1 bazillion arrows and run like a chicken

Better than walling it up 6 stories high or make a tree stand and build 10 million frost arrows. This feels more natural.

An Iron mace and a poison resist potion. Literally killed it twice in 7 minutes.

walled up with a portal to repair / heal /whatever & toe to toe.
After an incident, I beat him with a club. Anything blunt will do well. If you have frost arrows, you should also have frost hammer, and it probably tears him up. I don't do him out of order.

Being "very resistant" to fire and pierce damage means arrows is definitely not the best approach.

https://valheim.fandom.com/wiki/Bonemass

As already stated, mace works like a charm. I charge right up to the "sparkles" as he spawns and can get him down 30-40% before he begins moving. At which point it become a game of "ring around the skull." Charge - use meads - recover (and wait for mead cooldown timers) - repeat.