I added an English translation in your post. I know it takes extra effort to do this, but please translate your posts so we can all talk in the same language 
If you search on the forum for Tyrfina you should find people discussing it. However, Tyrfina has been buffed since its first release so maybe that will be a bit confusing. 🏆 Neo Monsters tier list (see first post) 🏆 has rankings of all the monsters. You can do a search “in topic” to see posts about the monster.
Tyrfina is rated above average for a mythic in the tier list. It’s a good monster for making a comeback. If the opponent is winning then Tyrfina comes and quickly gets a turn and can use the punish move to quickly kill an enemy or two. However, I think it’s a monster that is much better for people who already have lots of strong monsters. It’s a useful tool in a strong team, but doesn’t do enough by itself. There are many other mythics which are better for helping you build a strong team.