I remember watching this movie  it was probably back in 2013-2014 .it was a colorful animation movie it begains with a narrator telling an old legend about thunder and lighting as they fought all the time when they had little power remaining they made up and decided to place their remaining powers into a heart .

The original plot was about a forest that dwarf -like- creatures lived in it when they encounter a human girl *she was blonde * something happens and they decided to go on an adventure to look for that heart ,On their way they wanted to rest they found a place I think it was near a mountain under the Aurora borealis the human girl was singing & one of the creatures was annoyed of her voice so when she fell asleep he placed the -now cool ashes – of the camp fire on her Nose *or mouth  after that she couldn’t sing

When they found the heart one of them took it and it didn’t make him stronger like they expected it made him wiser on their way back to the forest one of the dwarfs shot the girl with an arrow. She died but the dwarf that took the heart was in love with  her he was crying and he was hugging her so he gave her some of his heart or something like that.

And that’s all I remember