??? Starting with where/how would be awsome
^be detailed
^please add a picture
Next time just search in the forum because it was already asked, frequently.
http://www.hunterislandforum.com/index.php/topic/322-lachzeers-location-guide-to-catching-rare-arkadions/ <- in this topic there is picture of where you can find Levi (which evolves in Leviathan )