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