Here is the full list of all 16 This Way Madness Lies achievements.
Get a pet
Defeat Ursathulhu
Use a unite ability at 100% power
Fill 4 or more item slots with items
Use the chat command
Complete a play
Answer a Shakespeare question correctly
Defeat Rosebud
Defeat Krakenthulhu
Defeat Yog-Titania
Defeat 3 ZombieZombieDa
Defeat Lady Macbeth
Defeat Edward De Vere
Complete the game
Meet a new ally
Use the battle command