Arcanus is a beautiful, vivid blue runed demon dog found in a pavilion just beyond the edge of Lake Kel’Theril in Winterspring.

The demon dog is inside the pavilion ruins on the left side of the lake (coming across from Everlook).  The location words “Ruins of Kel’Theril” appeared as I approached the spot.

Arcanus is located at co-ords 48, 59.  Level 54 rare.