Here is the full list of all 30 Astalon: Tears of the Earth achievements.
Defeated the Black Knight as the Gargoyle.
Reached the top of the tower as the Black Knight.
Defeated the Black Knight.
Finished the game with 100% completion.
Defeated the Gorgon Medusa.
Completed all entries in the bestiary.
Purchased all character specific deals in the shop.
Purchased all of Zeek's deals in the shop.
Purchased all of Bram's deals in the shop.
Purchased all of Kyuli's deals in the shop.
Purchased all of Arias' deals in the shop.
Purchased all of Algus' deals in the shop.
Completed 80% of the bestiary entries.
Gathered 100% of the tower's items.
Explored 100% of the tower's rooms.
Collected 50000 orbs.
Completed 50% of the bestiary entries.
Unlocked the collector Zeek.
Unlocked the gorgonslayer Bram.
Defeated the Gorgon Gemini.
Killed 1000 monsters.
Defeated the Gorgon Solaria.
Collected 10000 orbs.
Completed 20% of the bestiary entries.
Defeated the Gorgon Volantis.
Found the secret ending.
Defeated the Gorgon Tauros.
Killed 5000 monsters.
Defeated all the bosses in the Boss Rush mode.
Unlocked all secrets in the game and beat all the unlockable modes.