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