Please do not use Rune Transmute! There is currently an issue with this feature. We're working on it, and it will be fixed in tomorrow's patch, planned for Oct 9, around 5–7 PM PDT. This patch will also require you to update your game client.
FAQ
• If your game won't update, fully quit the game and quit Steam, then try again. If it still won't update, uninstall and reinstall the game. As a last resort, uninstall and reinstall Steam.