Here is the full list of all 26 Ampersat achievements.
Gain all Perks
Beat the Well's 100th level
Fully Upgrade Skadi's Statue
Make the Gem Merchant appear
Fill the Bestiary
Return all Lost Items
Fully Upgrade Well
Fully Upgrade Freya's Statue
Open the Portal to Lord Z
Capture all Bonus Words
Gain 3rd Ring Bonus Perk
Defeat all Dungeons
Fully Upgrade Weapon Shop
Gain 2nd Ring Bonus Perk
Fully Upgrade Armor Shop
Defeat a Tower
Gain 1st Ring Bonus Perk
Fully Upgrade Inn
Sniff out all Secret Chests
Open the Well
Capture a Bonus Word
Defeat a Dungeon
Find a Secret Chest
Gain a Rank
Consult the Bestiary
Ostensibly read the "How To"