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