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