Here is the full list of all 97 Divinity: Original Sin 2 achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Ifan: Forgive Lucian
Learn of the Council of Seven's location from Malady
Escape Dallis' siege on the Lady Vengeance after killing every minion
Lohse: Embrace your demon
Make a deal with Adramahlihk
Share Divinity with The Doctor
Gain the Villain tag
Force Dallis to retreat from combat in Fort Joy
Complete the game in Tactician Mode
Complete the game in Honour Mode
Ifan: Kill Lucian
Pray at every altar on the Nameless Isle
Escort Saheila outside without fighting the Lone Wolves
Kill Slane
Lockpick your way into Mordus' hidden lair
Tame Featherfall
Perform successful surgery on Natalie
Correctly answer all of Crispin's questions
Successfully begin a Game Master session
Successfully begin a match in Arena Mode
Fane: Return the Eternals to Rivellon
Purge Rivellon of all Source
Share Source with all of Rivellon
Fane: Embrace this strange new world
Ascend to Divinity
Complete the game in Explorer Mode
Complete the game in Classic Mode
Submit to the God King
Defeated the Kraken
Lohse: Banish your demon
Defeat Adramahlihk
Gain entrance to Lucian's Crypt without following the Path of Blood
Successfully walk the Path of Blood
The Red Prince: Kill the Red Princess
The Red Prince: Become the father of dragons
Persuade Toyseller Sanders to give you his amulet
Rescue Arhu
Beast: Ally with the Queen
Beast: Assassinate the Queen
Discover Reimond's Lair
Obtain Anathema
Arrive at Arx
Enter The Arena of the One
Convince Alexandar to ally with you
Use the Curse skill
Swear to the Covenant
Discover the hidden entrance to the Academy
Enter the Academy
Convince all party members to let you ascend
Sebille: Serve the Mother Tree
Sebille: Kill the Master
Sebille: Destroy the Mother Tree
Arrive at the Nameless Isle
Take the ferry to Bloodmoon Island
Learn of the Council of Seven's location from a higher power
Awaken the corrupted Ancestor Tree on Bloodmoon Island
Learn of the Council of Seven's location from The Advocate
Destroy every Voidwoken egg in Reaper's Cove
Receive Dorotya's kiss
Welcome Tarquin to the Seekers' service
Unlock your third Source Point slot
Craft a skill
Help free Mari from the Voidwoken
Kill Andras, the necromantic dog
Set Gareth on a path of reconciliation
Set Gareth on a path of vengeance
Serve Garvan the tainted stew
Unlock your second Source Point slot
Speak to an animal's spirit
Adopt Peeper
Become champion of the Driftwood Arena
Meet Meistr Siva
Arrive at Reaper's Coast
Escape Dallis' siege on the Lady Vengeance without killing every minion
Enter the Hall of Echoes
Craft a grenade
Take command of the Lady Vengeance
Craft a scroll
Defeat Alexandar in Fort Joy
Kill Radeka
Shapeshift into every race
Remove your Source Collar
Rescue Gareth from Braccus' Armoury
Arrive at the Sanctuary of Amadia
Equip runes to all of an item's available slots
Face a higher power
Kill an enemy using Teleportation
Escort the Black Cat out of Fort Joy
Flee Fort Joy for good
Use your first Source Skill
Get caught breaking the law
Win a persuasion event
Become champion of the Fort Joy arena
Gain the Hero tag
Arrive at Reaper's Eye
Escape the kraken's clutches
Perform a successful theft