Spoiler !!! First world

[Corius Gielian]

I don't know what to do with the poison. I've tried everything but i'm still waiting for the wrath of the goddess ...

[Jaime]

How did you even gained the poison? I saw tge bird, but I really have no idea what to do next

[Duke of Marlborough]

Same Question as Jaime. I have found the Bird and drunk from the Water. I also have put the Bird on the Podium, after a Rest, there were only Bones of him left.

[maxiemax321]

How do you even get a bird? Ive just met the gnome and thats it.....

[Skip mass, eat ass]

Corius - head to the northwest with the lantern equipped in the version of the First World where the Goblin is camped out. When you get as far north as you can (you should've passed SEVERAL trapped mushrooms on the way up there,) unequip the Magical Lantern and pass through the mist.

Jaime, Mariborough - you weren't supposed to drink the water. The goblin explicitly tells you this.
That aside, take the bird, place it on the podium, rest, take the bones, then make sure you are on the version of the First World where the Goblin resides. If you are, make sure you don't have the Magical Lantern equipped. Pass through the mist to the south, equip the lantern, head through the mist on the west, watch the cutscene, throw the bird's bones into the water, bottle up the water, then unequip the lantern and pass through any mist. Any mist.

If you're sure you're in the version of the First World where the Goblin exists, then follow the instructions I've outlined for Corius.

[wellard2006]

Pretty sure he's a gnome not a Goblin..

[kezientz]

Originally posted by 「gumiho god」:

Corius - head to the northwest with the lantern equipped in the version of the First World where the Goblin is camped out. When you get as far north as you can (you should've passed SEVERAL trapped mushrooms on the way up there,) unequip the Magical Lantern and pass through the mist.

Jaime, Mariborough - you weren't supposed to drink the water. The goblin explicitly tells you this.
That aside, take the bird, place it on the podium, rest, take the bones, then make sure you are on the version of the First World where the Goblin resides. If you are, make sure you don't have the Magical Lantern equipped. Pass through the mist to the south, equip the lantern, head through the mist on the west, watch the cutscene, throw the bird's bones into the water, bottle up the water, then unequip the lantern and pass through any mist. Any mist.

If you're sure you're in the version of the First World where the Goblin exists, then follow the instructions I've outlined for Corius.

ehm... im stuck at exactely that point.. how the hell are we supposed to figure that out? are there any hints at all?

[TreP]

The only problem I had there was figuring out how to get bird to die. All other things seemed intuitive.

Iirc you can ask gnome about short version of story, and he tells you what exactly you have to do.
Just to summarize, you need to:
Capture bird.
Place cage on stone
Click on campfire to sleep
Collect bones
Throw them into water
Get some of water
Use it on flower.