The Hearts of Stone Add-on for The Witcher 3: Wild Hunt has 13 achievements.
Defeat all the fallen knights and loot their campsites.
Provoke all Iris von Everec's Nightmares into fighting you at the same time and defeat them.
Recreate all of Iris' nightmares in the Painted World.
Buy all the items put on the block at the Borsodis' Auction House.
Participate in all the activities at the wedding.
Be under the influence of seven potions or decoctions at the same time.
Win a round of gwent with a total strength of at least 187.
Kill 20 cows.
Kill 3 opponents with their own arrows.
Collect all available Ofieri armor and horse gear, and at least one Ofieri sword.
Finish the "Hearts of Stone" expansion.
Kill the prince cursed into a toad.
Slide downhill uninterrupted for at least 10 seconds.