Here is the full list of all 43 Hellslave achievements.
You discovered the salt steppes east of Nivlatth.
You crafted at least one of Zurgul's items.
You crafted at least one of Bisith the Mage's items.
Your blows killed Beelzebub, Lord of Violence.
You defeated Baal, Master of Lies and Plague.
You inflicted an average of at least 30 damage per second.
You crafted at least one of Simeon's items.
The Priestess of Lust has gone back to the hell from whence she came.
Mammon, the Misanthropic Tyrant, swallowed his disdain along with his entrails.
Leviathan's lightning will no longer disrupt this world.
The Fallen Angel has been sent back to his fiery prison.
A strange Archon was guarding the forbidden fruit.
All 6 Infernal Demons have been defeated. You can now challenge the Anti-King of Hell.
You crafted at least one of Septhon the Aesthete's items.
You crafted at least one of Pegrarch the Pious's items.
You crafted at least one of Jacquor the Ingenious’s items.
You crafted at least one of Kamixiarisocl Iperpeniomicidus's items.
You crafted at least one of Balam's items.
You crafted at least one of Arbus's items.
You crafted at least one of Bisith the Unhinged's items.
Refrain from listening to the whispers of these ungodly weapons.
You crafted at least one of Septhon the Madman's items.
You crafted at least one of Pegrarch the Insane's items.
You crafted at least one of Jacquor the Exiled's items.
You crafted at least one of the strange Frail Servant's items.
After a tremendous effort, you've crossed the red line of humanity. Here's your reward.
You entered Hell. Run away, you fool.
You collected all the recipes and notes in Lore.
You listened to all the whispers from the anomalies.
You finished HellSlave. Do you dare try the Inferno mode?
You finished HellSlave in Inferno mode. You've proven your worth.
You inflicted an average of at least 90 damage per second.
You inflicted an average of at least 120 damage per second.
You inflicted an average of at least 170 damage per second. That's a lot.
You made all of HellSlave's recipes. It probably won't help you seduce any potential lovers, but props to you.