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