As of right now there are 10.
The First 5 are from Pre-order. (The code in most cases will be found on the receipt or in an email) They are
Thorn
Reyna
Montana
Marquis
Rath
The next 3 are from the Open Beta Challenges. (gratz on getting them all done) To get them just enter the SHIFT code
SWKTB-356W6-XC5RJ-XK6T3-HJ333. And you will get.
Shayne & Aurox
Benedict
ISIC
The next one is by Downloading Battleborn Tap and connecting your SHIFT account to it. When you do that you will get. (heads up it will not get the skin instantly on you Battleborn game. more info on the game here. https://battleborn.com/en/news/view/en-battleborn-tap-puts-25-heroes-at-your-fingertips/)
Orendi
Another easy one to get is by making a SHIFT account( you do not need to make a new, just got to have one) . You will get
Miko.
That is all for now i will keep it updated