there is a level 14 basilisk due north of blackbough, or whatever it is called. There is a peninsula on that piece of land, with a fast travel marker: "Harpy Feeding grounds." To the east and coastal tip from that fast travel, you will find the basilisk on a marked ?. to the west and other coastal tip of that fast travel, there is a tower with a drawbridge, and it has a level 14 wyvern. there is a hidden cavern in the water beneath that tower, also beneath a place of power. On that spot, you have place of power, underwater cavern with loot, and inside the tower you have one of the treasure hunts.
I also stubbornly tried to fight that basilisk while at level 4...gave up. Came back at level 10 or 11 and he went down easy. Same for the wyvern.