Backpack achievements
Backpack achievements depend on what your backpack holds: most unlock when you win a fight with a particular set of items.
Overflowing
Have 30 items in the storage at once
Reset
Recombobulate 8 items at once
Mother of Dragons
Win a fight with 4 different Dragons
It's Time For a C-C-C-Cardgame!
Win a fight with a Card chain of at least length 8
Tripple Bow Technique
Win a fight using 3 different Bows
Rawr!
Win a fight with 8 items improving Battle Rage
I'm the Library!
Win a fight using 4 different types of Books
Catch 'em All!
Win a fight with items from 4 different classes
Potion Master
Win a fight using 6 Potions
Bloodsucker
Win a fight with 8 Vampiric items
Archmage
Win a fight with 8 Magic items
I Am Cooking
Win a fight with 8 Foods
Multiwielding
Win a fight with 4 Weapons that use stamina
Buy Me More Jewelery
Win a fight with 10 Gemstones
Treasure Hunter
Win a fight with 3 Treasure items
Pig Farmer
Win a fight with 5 Piggies
Amulet Addict
Win a fight with 5 identified amulets