King Sprite
Your Pickaxe deals more damage. Increases in damage at each Level Up: 25% -> 50% -> 75% -> 100% -> 125% bonus damage
Punk Sprite
Possibly nothing... or infinitely something
(Perk is called "Ammo Magikarp" and "Infinite Ammo")
Dream Sprite
Grants a random item at each level, exploding with legendary loot at Max Level. Loot value increases at each Level Up!
Fire Sprite
Creates a fiery burst when you deal enough damage to an enemy! Required damage decreases at each Level Up: 175 Damage -> 150 Damage -> 125 Damage -> 100 Damage -> 75 Damage to trigger