Here is the full list of all 12 Adventure Time: Finn and Jakes Epic Quest achievements.
Beat the game
Max out your weapons with Billy
Complete 5 Key-per quests
Collect 5,000 gold
Find the Jake's Pups scroll
Unlock a 5 key chest
Earn a 25 hit combo
Defeat 25 evil pigs
Collect an artifact
Level up Finn & Jake
Switch characters
Identified 10 pages with PB