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