Here is the full list of all 14 Buriedbornes - there are Dungeon RPG achievements.
Kill "Old Prophet".
Score 1,000,000+
Kill 1,000+ monsters.
Slay "Ancient King".
Score 10,000,000+
100+ Death
Clear 100F
Pick 1,000+ equipments up
Pick 1,000+ skills up
Encounter 1,000+ events
Kill 100+ roamer.
Clear rank2+ dungeon.
Clear rank3+ dungeon.
Clear rank4+ dungeon.