Similar to the Villager Quest the End pass requires you to kill a number of mobs to claim a tier. However Instead of getting a villager egg you will get:
Custom items
Bossfight unlocks
JonGames currency
For every kill you get on a custom end mob (Eg, Reaver, Endbear... Etc) You will gain end score towards the End Pass. You can also see how many points you have by hovering your cursor over your player head in the end pass menu.
End Bear = 6 points
End Bear Cub = 2 points
Ottter = 2 points
Ottermancer = 8 points
The Unfed = 8 Points
Arch-Phantom = 12 Points
Reaver = 5 points
Frightended Enderman = 8 points
Cultist = 5 points
End shadow = 10 points
Paladin = 8 points
Poisonous Mushroom = 4 points
Angel = 8 points
Rotten Bark = 8 points
Masked Stranger = 50 points
End Bear Keeper = 50 points
Skeleton King = 10 points
Ender dragon = 10 points
How is it obtained?
It can be obtained by buying it at a spawn adminshop. Or it can be found at an Aether biome in the end.