Here is the full list of all 50 Eldest Souls achievements.
Perform 3 Perfect Counters in a row against any Boss.
Obtain the Empty Vessel
Finish the game without activating any Shard or Infusions.
Gain the Abyssal Eye
Gain the Kindled Heart of Fire
Gain the Blessed Hunter's Charm
Gain the Blessed Trueice Prism
Reach the ending without dying once.
Defeat Eksyll in Abyss Mode.
Defeat Aryana in Abyss Mode.
Defeat The Warden of Purity in Abyss Mode.
Defeat The Deer God in Abyss Mode.
Defeat Drakmur in Abyss Mode.
Defeat Hyem in Abyss Mode.
Defeat Azikel, God of Light while taking 0 damage.
Defeat Azikel in Abyss Mode.
Have at least 10 Windleaves active at once.
Defeat Eos in Abyss Mode.
Maintain 4 stacks of Berserker for 30s.
Defeat the Guardian while taking 0 damage.
Defeat the Guardian in Abyss Mode.
Defeat the Watchdog while taking 0 damage.
Defeat Eksyll
Hit enemies with a Shard attack 200 times
Reach the Steps of Ascension
Defeat Drakmur, the Nightmare while taking 0 damage
Defeat Drakmur, the Nightmare
Deliver the bag of crowns to Edelon.
Defeat Hyem of the Frigid Waste.
Defeat Hyem while taking 0 damage.
Gain the Blessed Feather of Dawn
Defeat Aryana, First of the Moon.
Defeat Aryana, First of the Moon while taking 0 damage.
Defeat The Deer God and the Warden of Purity while taking 0 damage.
Defeat The Deer God and the Warden of Purity.
Reach Concord Sanctuary
Defeat Eos, God of Unity while taking 0 damage.
Defeat Eos, God of Unity
Defeat Azikel, God of Light.
Reach the Crossroads
Defeat the Guardian.
Hit an enemy with Windslide, Berserker Slash, or Counter 20 times.
Hit enemies with a thrust attack 200 times
Retry a Boss 10 times in a row.
Talk with Rass
Deliver the harp string to Edd
Defeat the Watchdog.
Die to a Boss.
Die to a rolling log.
Reach Crusader's Landing