For Hearthhull, I think it comes down to the fact that this deck is dumping tons of lands into the graveyard and it most likely wins the game by bringing them all back in one go - using a card like Splendid Reclamation - for a mass of triggers
While I'm tempted by all of the above, I'm leaning toward the binders most of all
Let's take things up a bit, shall we
Its not just mechanics and keywords that make a return here either, as there are a number of incredibly cool reprints that bring new cards into Modern from previous sets
7 Loose Packs At the bottom of the totem pole are loose packs, as these are the most basic Prismatic Evolutions product you can get, with each pack containing ten cards from the set
Mana Echoes Like Molten Echoes, this is also nuts with Siege-Gang Commander, seeing as youll generate a ridiculous amount of mana