Below a list of working AMP codes that can be redeem under settings in the game.

Alien Ooze - ooze14
Asteroid Shards - ashard
Chest - chest3
Chest - chest4
Chest - chest6
December Birthstone - sapphire3
Gold - gold16
Green Mushroom - green
Pumpkin Chest - spoopychest
Rare Spooky Candy - 2spooky
Rare Spooky Candy - boo
Rare Spooky Candy - creepy
Rare Spooky Candy - pspoopy
Rare Spooky Candy - spooky
Red Mushroom - red
Sappheiros - sapphire2
Stream Jade - jade4
Tumbleweed! - tumble7
Turkey Chest - gobblegobble
Witch Grass - tumble8