Here is the full list of all 11 Enter Digiton achievements.
Obtain your very first shield.
Kill Belzaboul.
Kill Marshal Rabbit.
Kill Asmodai.
Kill Akaman.
Obtain 100% completion.
Interrupt a secret snowman meeting.
Find the Lone Knight.
Kill Corrupted Belzaboul.
Kill Corrupted Asmodai.
Kill Corrupted Leviathan.