Here is the full list of all 40 Spiritfall achievements.
Defeat 3 enemies in a single room using Wall Splat damage as the final blow.
Defeat a Blightborn enemy 3 times in a single Hidden Rift.
Pick up a Relic while having 3 Relics equipped.
Safely traverse the Outskirts.
Give Yara's Mystery Mix a try.
Safely traverse the Viridian Trail
Safely traverse the Burrows.
Destroy 10 Training Dummies.
Buy all the items from a single Celestial Exchange shop.
Display an act of avarice in front of a Statue of Kismet.
Get forcefully ejected out of a Hidden Rift.
Equip a Spiritforged Mask.
Upgrade a single Spirit Blessing with 3 Luminous Gems.
Purify a Stray Soul.
Safely traverse the Frigid Veil.
Fail during a Relic's tinkering process.
Level-Up a single Relic 3 times in one run.
Pet the Turtle.
Purchase something fresh from Yara the Herbalist.
Unlock all Spiritforged Masks.
Uncover all Synergy Blessings in the Codex.
Unlock all five base weapons.
Awaken a weapon.
Uncover all Divine Blessings in the Codex.
Dismiss a Divine Blessing through a Dust Effigy.
Complete all Skill Trees at the Perennial Flame.
Encounter and defeat all Mini-Bosses.
Destroy a Training Dummy by moving it outside of the Training Area.
Defeat the Enduring Sentry under the effects of the Perennial Tactics challenge.
Defeat the Dark Trinity under the effects of the Perennial Tactics challenge.
Defeat the Heretic Warlock under the effects of the Perennial Tactics challenge.
Defeat Tasmos, Head of the Order under the effects of the Perennial Tactics challenge.
Unseal the Great Gate.
Complete a run while having at least 15 blessings from a single spirit (including Synergies).
Defeat the Pursuer Guardian in the Outskirts.
Safely traverse the Brink.
Purchase 8 items from Yara the Herbalist in a single run.
Defeat the High Priestess under the effects of the Perennial Tactics challenge.
Unlock all Alternate Weapon Forms.