The first think you need to do is go to Flosshilde and go to the highest point and find the Dungeon like you see on the Map in the Screenshots

Enter the Dungeon if you find it, if you can't write a comment.

After you enter the Dungeon go to the Point on the Up Right on the Map and there he is just Talk to him there is no Fight if you talk to him.

After you Talked to Santa don't try to enter the Portal behind him there is just a Boss Fight like in every single Portal in this Dungeon if you don't want to lose/die try to Avoid it because the boss is
lvl 900 and not really that easy if you are trying to fight him like me with LVL 525.

<<<<<This is the Portal i am talking about>>>>>