All the remaining art for Helheim #s 1-3 is now with Cadence Comic Art and for sale exclusively through them. You can find it all here through the link. They also currently have the full set of Phantom Variant covers, and will be handling Helheim art sales from here on out.
The series is now completely drawn! #4 came out this week, and so we'll be done as scheduled in July. Here is the cover to #6, colors by Nick Filardi.