Here is the full list of all 24 Source of Madness achievements.
Complete Act 3.
Arrive at the living planet for the first time.
Complete Act 2.
Dash 2000 times.
Die while having at least 5000 gold.
Reach Platue of Leng for the first time.
Defeat 500 Monsters.
Complete Act 1.
Reach the Tower of Madness for the first time.
Reach the Blood Worm for the first time.
Use Evenstar to upgrade the Altar.
Defeat 100 Monsters.
Enter a Magic Shop for the first time.
Enter a side area for the first time.
Defeat 10 Monsters.
First time exiting the Tower of Knowledge.
Defeat 5000 Monsters.
Defeat 10000 Monsters.
Burn 150 Monsters.
Get poisoned 150 times.
Buy 100 items.
Open 200 Chests.
Unlock all classes.
Unlock all upgrades.