There are two kind of rukh in Magi universe. But first, let me explain what is rukh. SO basically, the rukh is:
Rukh is the home of souls. While we live, it is every man for them self. But when you die, all go back to one place, This is Rukh. When humans die, their bodies return to the earth don't they? The souls return to Rukh, The home of souls.
And there is Black Rukh, which mean the polar opposite of Rukh. It is created when one goes against fate and tries to defy destiny. It is created from and fuels hatred and malice.
According that, we know that the true rukh at the end, will come to one place called home of souls, but what happens to Dark Rukh? Where will their souls go? Do they go to Hell or something? And what is the home of souls, is it what we would call Heaven?