This is a deck based around getting your opponent down to a zero cards in their hand and plently of creatures in all graveyards so that the two big Avatars can be summoned for very little mana.
In the early game we will be forcing our opponent to discard cards aggressively while discarding cards ourselves to later reanimate or exhume later when we need them. Here's a card by card breakdown showing tactics and synergy:
Careful Study Ideally you want to get an Island down first turn and use this card. Use this card to ensure you get an useful cards in your hand and make sure you discard creatures for later that can either be reanimated with Unearth such as the Shadowmage Infiltrator or the Hollow Specter. Or even put one of the Avatars into the graveyard to bring back to your hand later with the Undertaker when the summoning conditions on either Avatar are met.
Unearth A nasty card that can really surprise an opponent. If used on turn two after a Careful Study you can bring back some horrible stuff such as previously described. It will really turn up the heat on your opponent as these cards when reanimated can force early discards from your opponent.
Ravenous Rats
A low cost reusable utility creature that diminishes the hand of your opponent. Works really well in this deck as it can be a target for Unearth or else it can be returned to your hand to recast later using the Doomsday Specter. Don't worry about it dying early on, its main purpose is to force the discard and to annoy any small attackers.
Undertaker What a great card this is. Discarding a card shouldn't be seen as a detraction in the case of this deck and we can use the Undertaker to bring back all the annoying creatures for further upset to your opponent. Earlier discarded creatures that have some how died can just be recast at low cost making this deck very hardy, the undertaker is useful throughout the manacurve.
Shadowmage Infiltrator A huge fan of this card. A near unblockable creature that takes away your opponents life and cards for only 3 mana. This is a big threat and with 3 toughness is fairly difficult to remove. Works well with Unearth and acts as an accelerator to speed up the casting of a discounted Avatar.
Hollow Specter Much the same as the infiltrator, this creature is another low cost way of reducing an opponents hand for the purposes of the Avatar finisher. Very annoying.
Stupor
Nice. This card is useful in any black deck and very efficient at what it does and how it lends synergy to what this deck is trying to do.
Doomsday Specter One of the best gold card creature returners ever reprinted. Use it to get a Ravenous Rats back to your hand and pile on further misery. By this card your opponent will have or rather should have a reduced hand of 2 or 3 cards so this creature will serve to proliferate that process further.
Avatar of Will
This creature although massive can be a game changer particularly when you consider it is possible to have it show up as early as turn 4 but more oftenly by turn 6 for only UU. A flying 5/6 is a tough challenge.
Avatar of Woe Also at around turn 6 it is conceivable to get out the other Big Sister for only BB when you have been using the Careful Studies effectively and also decimating the opponents hand. Any way you look at it this card is going to cause absolute nightmares for your opponent and should wrap up nearly all games.
Enjoy!
