It’s OFFICIAL:

You can only acquire a Fenrir (lvl150) after defeating the Fenrirsūlfr (Fjourd boss) the resulting tame is delivered in a cryopod after the boss dies.

The reason Dododex say it’s a knockout tame is because if you spawn a wild Fenrir you can knock one out and tame it that way, the only down side being the Fenrir CANT spawn in the wild

The way to tame this creature is to kill the final boss on fjordur.

To tame this creature you must kill the final boss on fjordur. Everyone else is either lying or tamed the modded version. Currently, there is no other way to get one.

It's not a wild creature, you get 1 fenrir in a cryopod everytime you beat the end games boss of fjordur

Defeating the Fjourd boss gives you a level 150 Fenrir in a crypod

Single player tested

!Not a knockout tame! This creature is tamed after defeating the final boss

You get it from defeating a boss

You have to kill the main boss to get if you want a high level kill alpha and better stats if you want to just get to use it go gamma but it really won’t be worth just go for alpha

These look pretty fierce. Wonder if they'll freeze things too. Maybe a frost bite that slows creatures down.