This mystery can be found in northeast Eurvicscire, just northwest of Picheringa.
How to Defeat the Boar and Wolves in Fly Agaric: Eurvicscire
When you arrive at the site you’ll find some mushrooms on a rock. Interact with them to begin the mystery, and you’ll soon find that this one involves defeating two large mythical boar from Jotunheim, and three regular wolves. The fight should be relatively easy but you’ll need to be careful and not get caught off guard by any of the animals. Both the boar and the wolves have the ability to knock you down on the ground with a charge attack, so you’ll need to be ready to dodge or roll out of the way whenever you’re susceptible to one.
There will be no new enemies that spawn other than the initial boar and wolves, so you might as well use any powerful abilities that you have at your disposal. You should especially focus on using area of effect abilities such as Throwing Axe Fury or Incendiary Powder Trap, or if you have any which can summon allies such as Man’s Best Friend or Irish Wolfhound, these will help to distract some of the enemies while damaging them at the same time. Ultimately, you’ll want to do as much damage as possible to all of the enemies and reduce their numbers as quickly as possible, thereby reducing the chances of you being knocked over and overwhelmed.