Deck Concept: Wanted to make a demon themed deck, but realized that 1) demons don't really have a specific mechanical theme or much tribal support, and 2) I didn't have enough good demons in any 1-2 elements to make a good deck without adding a *lot* of extra other stuff, so I opted to make a 4 element deck with the best demons I had across all the elements. There's not much voidwalk here, but harbinger should still be able to help you get some things out ahead of curve and/or drop them aggressively if you get some decent portal locations. The deck would probably be better served with an elementalist or seer, but I stuck with harbinger for flavor
Strategy: The closest thing demons seem to have to a theme is genesis effects, many of which will end up damaging you when they enter - for that reason you generally are going to want to play this deck pretty aggressively to push the tempo of the game, take control of the board and try to kill your opponent before the fact that you put yourself at half health becomes a problem. You do have several mid-late game menaces in the deck with the Lords, , and , and because you're harbinger hopefully you may well be able to drop one of those turn 5 (or even 4 if you luck out with the exact right combination of portal location, elements, and one of the 
1 towers or a