Using the Heartless Summoning + Myr Retriever + Myr Retriever combo, we can create endless loops of Mill, Card Draw, and Life Loss.
Heartless Summoning + 2 Myr Retriever + ...
...Altar of the Brood: If played on Turn 1, this will allow us to completely mill our opponent's deck before they can play their second land. This is also the combo of choice when using our next card. If we have the combo in our hand, we can mill the opponent on turn two.
...Grim Haruspex: This will allow us to draw our entire deck if we need to. Once we have all of our cards in our hand, (except for leaving 1 card in our library), we then destroy it with Perilous Myr to prevent us from milling ourself and losing the game, play Altar of the Brood, and then start the mill combo. If we have all of the necessary cards, we can do all of this on turn 3.
...Falkenrath Noble: This acts as a Blood Artist in our deck. Performing the combo will allow us to cause infinite life-loss. If we have the combo in our hand, we can do this on turn 3.
However unlikely it is that we would have Heartless Summoning, 2 Myr Retrievers, 2 Swamps, and any one of the other cards in our opening hand, it HAS happened. If it doesn't happen, there are tons of ways to draw or tutor for the cards we need.
Street Wraith, Phyrexian Rager, Sidisi, Undead Vizier, and Grim Haruspex all help us get to where we need to be.
Solemn Simulacrum, a recent addition to the deck, will help us out quite a bit by thinning out our deck, and drawing us cards.
Duress will give us information about the opponent's hand/deck, while getting rid of a problematic card from our opponent's hand.
And lastly, Perilous Myr, while primarily being used to destroy our own Grim Haruspexes, can also be used to get rid of any smaller creatures that could cause problems, like Eidolon of the Great Revel.
The sideboard gives us an additional style of deck that will throw off the opponent if they sideboard against our "combo". If we think that the opponent is preparing for the combo, we can sideboard out into a devotion deck, which the opponent may not be prepared for. Since the most important pieces of our combo that are non-creature spells, it's probable that our opponent will sideboard out the main-deck creature removal in favor of artifact/enchantment removal. This plays well into our favor since Heartless Summoning isn't required to succeed with the devotion strategy. Sideboarding out the Myrs and Altar of the Broods will make room for the entire sideboard.
Let me know what you think of the main deck, and the sideboard strategy. The deck is incredibly fun and unexpected, and is light on the wallet.
