This deck doesn't really need much explaining, as Tergrid works in obvious ways.  I do, however, feel like mentioning that I tried to lean on opponent sacrifices more than discards since those will always be permanents we then acquire, while discards can/will also be non-permanent cards.  I tried to go for repeated effects over one-time effects, so ETB/death-triggered cards are very few in the deck.  I also tried to focus on sac/discard effects that hit each opponent, versus a single player, as well as trying to minimize effects that hit us in the process (although creature/permanent sacrifice effects are less impactful on us, when we can usually sacrifice a card that we acquired from an opponent).  If it's a one-time effect, then it better do a LOT, or come tied to other effects we want as much or more.  I also tried to include a lot of ways to make our opponents draw extra cards, but preferably usable/activated on our turn, so we can easier force them to discard those cards... if they draw cards on their turn, they'll more than likely have a chance to play them (which is bad if it's a board wipe, etc).  Because of this, I pulled Ghirapur Orrery and Font of Mythos out, because they put so many cards in our opponents hands on their turns, where I left Howling Mine in because it's only one extra card each turn (but you could easily justify pulling it out too).  Similarly, I left Master of the Feast in, even though we don't get to draw from it, because it's triggered on our turn, plus it's a 5/5 flyer for 3cc.  The deck does contain a few expen$ive cards, so the Maybeboard is full of backup options.

There are four Zendikar Rising flip-lands in the deck, so the total land count is 34.  Including cards that force our opponents to sacrifice lands (Pox, Smallpox, Desolation, etc), which you then get with Tergrid, I count 16 nonland sources of "ramp", plus another six land sources (like Cabal Coffers and Nykthos, Shrine to Nyx).  But with Tergrid's ability to help you steal your opponents' land and other ramp permanents, the total might be overkill.  However, there are 19 cards in the deck that will help us draw (or tutor) extra cards, plus another three that have everyone draw/discard, so the extra mana available won't be going to waste tooo often.

Even though we'll be stacking up cards in our graveyard, there isn't tooo much recursion in the deck, or at least not as much as you might expect in many mono-black decks.  As is, there are only six recursion cards to get creatures back from the grave.  But there aren't really any cards/creatures that are crucial to our ability to win, other than Tergrid.  The goal is to beat our opponents to death with their own creatures and ours, and/or with cards that dole out life loss or damage.  On that note, there are no infinite combos, as IMHO none are necessary here.  Tergrid is a big enough dick just by himself.

Memory Jar is a fun card in here, as it forces each opponent to draw and discard 7 cards, which puts all those permanents into play for us (assuming they couldn't cast them with flash, etc).  Not a cheap card to buy, but very effective with Tergrid!

Rankle, Master of Pranks is Tergrid's best friend... force each player to discard, to sacifice a creature, and to draw a card, which fuels more discards... that's the optimal trifecta for Tergrid... a sac outlet is about the only thing that could make him better.

Myojin of Night's Reach is tempting to put in, even with its 8cc cost, except for the fact that we should be forcing our opponents to have and maintain a hand of close to zero cards well before we can afford to cast the Myojin, making its value/cost ratio pretty bad.

As long as you are playing it a bit into a developed board state, and players have enough cards in hand, and creatures in play, Possessed Portal can be a wincon with Tergrid.  It triggers each turn, forcing everyone to sacrifice a permanent or discard, meaning your board state will increase rapidly the more players are in the game.  If no one has a board wipe, then you will effectively end up with everyone's lands and permanents, before you sacrifice Possessed Portal to itself.  But the more players in the game, the more turns it triggers, and the faster you acquire everyone's stuff before their next turn comes around... not that they could draw a card to increase their hand or board state anyway.  It should get everyone to scoop once they realize its long-term effect, assuming no one has any removal or a board wipe in hand.

In a similar fashion, Death Cloud can also be a wincon, simply from the land you steal from your opponents after they sacrifice them, not the mention everything else they'll be discarding or sacrificing.  It won't help you get their noncreature/nonland permanents, but after all is said and done, that shouldn't matter much.

Mind Slash is gold in this deck, as you can sac unimportant creatures acquired from opponents, then force them to discard other permanent cards you want... like bigger/better creatures, or maybe their lands or ramp...?  There's nothing better than a Thoughtseize on a stick! ;)