Preview - Return of Prince Lev'Lar + Special Suggested Vanities

[Cinco]

is it as easy to spawn him at level 15 as it would at 110? Or is there a spawn rate per say?

If you're not hunting for him in the Level 110 campaign with the Elixir active, you'll only get him to spawn from popping chests.
Running in "Legend of Ebonthrax" with the Elixir gives you a chance to spawn him from a monster (and there are lots of those).