It is the Hardest Mini Boss because of his Armor, but I used a High level Velonasaur with melee point and I took him down, an army of magmasaurs or rock golems could probably do it to, maybe a Yutyrannus can improve your chances. Up if you found helpful.
Steinbjörn
Steinbjörn is a boss in ARK: Fjordur.

Player-written tips for taming, using, and fighting the Steinbjörn in ARK: Survival Ascended & Evolved.
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.
Fourth tip: different person It awesome looking bear
20 1k Maylee shadowmanes each doing 50 damage
U was there for 2 hours
Corner ledge, velonasaur, 25 minutes of ur life. Steinborn = dead
The hardest one of the worldbosses (imo) had crazy damage resistance when I fought it and had 300k health
Not sure if this is for everyone else but the dermis seems to be broken for me, it just shows up as a regular direbear and not the boss's form
Use runestones from alpha creatures to summon it in, in Jotunheim.
Alright so Heres a good tip.
Noooo u dont need mutated gigas or rexes, u just need a velonasaur(from the fire wyvern island), crank up to abt 600%+ dmg and use a grapple to get on one of the ledges and then just shoot him from the cliff, he cant get to u, therefor keep some…
Alright so Heres a good tip.
Noooo u dont need mutated gigas or rexes, u just need a velonasaur(from the fire wyvern island), crank up to abt 600%+ dmg and use a grapple to get on one of the ledges and then just shoot him from the cliff, he cant get to u, therefor keep some health stuff like blood or brew, a few stones will hit u for small damage.
Blood stalkers have a amor piercing attack so use some front blood stalkers
Gigas are the way to go, rock elementals do the second most damage against it.
The magmasaur is hit strong
Your best bet is something that deal explosive damage like magmasaurs or shadowmanes not only are the not affected by the bears armor but they deal extra damage. Phoenix does as well but unless you have an army of god tier phoenix I do not recommend it.
A good way to defeat this bear is to use velonosaurs as they do enough damage to bring it down, you can also use gigas and rock elementals. If your on your own without dinos you can use a rocket launcher with homing missiles while being grappled to a wall with a crossbow and…
A good way to defeat this bear is to use velonosaurs as they do enough damage to bring it down, you can also use gigas and rock elementals. If your on your own without dinos you can use a rocket launcher with homing missiles while being grappled to a wall with a crossbow and grapples as this works quite well too..
Fly to ledge at the back of the cave in then un cryopod a descent velonosaur. Bring milk.
Third tip! It’s cute. No? Is it just me?
My tip on killing this boss is by getting 3 high level reapers and a yuty it is a powerful combo because of the damage and resistance
Use Velos on the cliff with vines, use climbing picks or grappling hooks and if you position your velo correctly it can’t hit you. Try to bring a friend and you both have 140+ wild tamed velos with like 4k+ Stam and good melee
To kill use the amargasaurus armor break spine to remove the damage reduction and then kill it with gigas
Carcha are good for this one.