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