I can't find "The Big Finish" quest anywhere, I finished everything in Asgard but this quest. It's also blocking me from getting the last stone.
I saw all YouTube videos about the area but everyone is getting the quest when talking to the builder, but I'm unable to talk with him.
Hi @m-omari and welcome to the forums.
I'm sorry to hear that you are experiencing issues with the quest 'The Big Finish'.
The quest should begin after you complete the quest 'Forging a Bond'. You are required to examine the builder's tower and the builder should be inside and you should be able to talk to him.
If possible can you load a previous save before the last quest you completed in Asgard. However if this is not possible then could you please provide a video so that I can see the issue that you are experiencing.
Can you show the following in the video:
@m-omari Thanks for the video provided.
I have watched the video and can see that 'Taking Root' is still an active quest in your quest log which is strange as that quest needed to be completed before the 'Forging a Bond' quest can be completed. Do you recall if you already did that quest?
Can you try tracking the quest 'Taking Root' to see what happens.
What is supposed to happen is you complete the quests 'Taking Root' and 'A Feline's Football' and this should trigger a cutscene with Ivaldi and Freyja then the quest 'Forging a Bond' should complete and the 'The Big Finish' quest should appear in your quest log.
@m-omari I'm pleased to hear that the quest appeared for you after completed the other quest 'Taking Root' 
devtrackers.gg