If Geralt and Regis investigate the playroom at the Beauclair Palace in search of Syanna, they will find a journal containing the Land of a Thousand Fables. This will lock you into "Beyond Hill and Dale" in The Witcher 3: Blood and Wine, which has some essential and missable things to do. If you want to get the best ending in Blood and Wine, then it's vital that you follow the walkthrough below and make the same decisions we do!
Follow the Yellow Brick Road & Defeat the Wicked Witch
As you arrive in the strange fable land, follow the Yellow Brick Road north, where you will come across an Archespore at a bridge. With the Archespore dead, jump across the collapsed bridge where you will eventually meet Syanna, who is arguing with the Wicked Witch. This will begin a boss fight.
The Wicked Witch will fly around while protected by an impenetrable bubble. To defeat the Wicked Witch, use Aard or your crossbow when she cackles, as she will lower her bubble to spray the ground with her poisonous soup. This will cause her to fall down, and you should destroy her Broom so she is stuck on the ground and ready to be slain by your sword!
When you speak with Syanna, and she asks why you are here, make sure to say "Came to free you." This will help with dialogue needed for the good ending.
With the Wicked Witch now dead, you will need to follow Syanna to Joss, but on your way, you can grab some unicorns, which will act as your mode of transportation in this rather large realm. When you find Joss, you need to kill the wolves and ask him about the magic beans.
Find the Red Bean (Three Bears & Little Red Riding Hood)
The first bean to start with will be the red bean. Head south, and if you follow the path to the left, you'll find a cave with the three bears. They're all asleep, and Goldilocks is dead at the table. If you pick up the magic food from the table, they will attack you, but there's no reward for any of this, but it's just on the way.
Continue through the cave, and you'll find the Big Bad Wolf, who tells Geralt and Syanna that he has killed Little Red Riding Hood and the Hunter, and thrown their corpses in the well. You need to jump into the well, swim down to loot Little Red Riding Hood's Hood from her corpse, and then swim out of the cave.
When you resurface, Syanna will wear the Red Hood and "play" with the Big Bad Wolf, beginning a boss fight. He acts like any other werewolf, so Devil's Puffballs and Beast Oils will make quick work of him. Regardless, once he's dead, loot his corpse for the Red Bean.
Syanna will ask you if you want to know what happened to her as a child, and if you want the good ending, it's essential that you select "All right – tell me what happened."
Find the Blue Bean (Three Little Pigs)
With the Red Bean acquired, it's time to head east to find the three little pigs. Their brick house is standing on a hill, and you can blow it down with Aard. This will cause the three little pigs to attack, and they're surprisingly strong, but it's nothing a good silver sword can't deal with.
With the three little pigs now slaughtered, head into the ruins of their brick house, and you'll find the Blue Bean on a table inside. Syanna will comment on your sense of humor, but how you respond has no bearing on the story or consequence.
Find the Yellow Bean (Longlocks)
The final bean is with Longlocks, who is locked away in the large tower. However, before you go to the tower, go south of the water to find a corpse, which you can loot for the full Toussaint gear set and the Vitis sword.
To climb Longlock's tower, just vault up the stairs and head inside the middle, where you can take the stairs up to the top to climb the scaffolding. However, when you enter Longlock's chamber, you'll find that she's hanged herself with her own hair.
Longlocks will now be a Wraith that you need to kill, and she will regenerate health if you do not kill the corpses that are summoned to her. Just use Specter Oil to kill her, and then collect the Yellow Bean from her bed.
You can now head out her window to find a plank of wood that can be used to jump safely into the water below!
Syanna will talk to you about how she met Dettlaff, and it's important that you listen to her story for more progress toward the good ending.
Obtain the Ribbon From the Girl Who Sells Flint
Once you have all three magic beans, do not plant them. Instead, take a detour south toward the girl who sells flint. It's vital that you get the ribbon from her, so either play her at Gwent or pay the 500 Crowns. Either way, you need the ribbon, or else you cannot get the good ending.
Plant the Magic Beans and Defeat the Cloud Giant
You can now plant the magic beans, which will make you leave the fable town, so if you want to explore, make sure you do so before planting the beans! After planting the beans, you'll have to fight the Cloud Giant, who is weak to Ogroid Oil and the Igni sign. You can also bait him into hitting the electrified cages to stun him!
Syanna will ask to have her way with you, and this activates an optional sex scene. Your decision here does not impact the story or have any consequences for your romance partner of Triss or Yenn.
With the Cloud Giant dead, you can enter the castle and leap into the well, which will spawn you back in Beauclair, where Regis will greet you. You can tell them both to shut up, or side with one of them, as this also has no bearing on the story.
You will now be locked into the next quest, Tesham Mutna, and if you managed to get the ribbon, you will always be forced to fight Dettlaff. If you didn't get the ribbon, then Dettlaff will always kill Syanna.
Source: Game Rant