why not use Aranna Starseeker from Hearthstone as your Vengeance Demon Hunter instead of Kor'vas Bloodthorn? Aranna is canonically vengeance anyways, and is a more recognizable character imo (being one of two demon hunters represented by the player in that game). As much as I want to see a true Havoc DH in hots, I think Illadin has that corner of the market on lockdown, and having a vengeance DH added to the game will only put Kor'vas farther back on the ever expansive list of heroes.

there is more to be done for sure, things that need tweaking and rewording and some numbers to clarify, but this is the basis of how I picture a Druid Multiclass in HOTS.