Strong Core / Flexible Outs

Core;
  
They form the backbone of the deck. The Nazgûl present a synergistic threat density that can override all but the most prepared control mages. The above rate Winding Constrictor adds some brawn to your blocking while also growing your Nazgûl lineup by orders of magnitude. While Assassin's Trophy offers a stong, flexible out to whatever the opposing mage hangs their victory on.

Backing them up,

The A-Moss-Pit Skeleton and Claim the Precious support the ring-bearer with looting, as well as clearing the way with temptation. Forming a value engine with the ring-bearer A-Moss-Pit Skeleton can also be a strong late game recurring threat with a beefy statline to support your dwindling population of Nazgûl. The Claim the Precious gives another couple of temptation triggers while also adding support allowing your Assassin's Trophy to be pointed at more threatening non-creature permanents.

Ending out the core includes we have some deep filtering with Assemble the Team allowing you to find one of the many outs when you need to. Urborg Repossession makes certain that your enemy pays multiple times to get rid of your most threatening permanents and creatures.

Support;

Temptation, one of the core mechanics of the deck gives you access to filtering as well as some incedental odds and ends.
Call of the Ring will win you games with the speed it powers up your Nazgûl and allows you flexibility when assigning ring-bearing on a turn by turn basis. This allows some interesting board wipe potentials against going wide strategies combining the third step of temptation with an Ochran Assassin ring-bearer. Sméagol, Helpful Guide can turn games around dumping valuable outs into the opposition's graveyard while ramping you into an impressive land count.

Recursion, while being initially confusing, Gyox, Brutal Carnivora especially on a board with Winding Constrictor can quickly refill a library that has been depleted by mill or to gain the upper hand in long drawn out grindfests. Journey to Eternity // Atzal, Cave of Eternity can protect a valuable ring bearer allowing it to act fearlessly while also keeping your board stocked well into the late game with recusive Nazgûl being tremendously oppressive. Find // Finality being an amazing Stall Breaker also has a place early game to get you back on the upper hand against removal heavy openings.

Stall Breakers, like Find // Finality allow you to navigate tricky board states with ease. Legion's End with it's ability to clear entire armies of tokens, and Driven // Despair letting you smash trough enemy lines with your beefy Nazgûl squad without having to worry about the swingback. Shadowspear while letting you kind of blow for blow against even the most healthy life gainer strategies, has the added benefit of allowing your Assassin's Trophy to bypass pesky indestructable and hexproof oracle text. While mentioned as a potential ring-bearer Ochran Assassin shines when your Nazgûl just need something to open the gates to the opponents life total.

Must Answers, finally are threats that give your Nazgûl breathing room from enemy removal as well as being demoralizing blows against the opponents morale should they manage to stick around. Since their inclusion plansewalkers have been tremendous in their ability to turn the tide of games. Vraska, Golgari Queen lets you get rid of creatures that Gyox, Brutal Carnivora has got oily, while also having an ultimate that never lets the opposing mage rest. Vraska, Regal Gorgon is great at turning every creature into a ligitmate threat. Garruk Relentless // Garruk, the Veil-Cursed give you a steady supply of fodder for sacrifice and even can grab you creatures that you need in a pinch. Other than the planeswalkers Glissa Sunslayer has a habit of ending games just by nature of being on the board.

Conclusion, while this isn't a deck that I can pitch for it's accessibility it is a deck that rewards you for knowing it contents and using every tool at your disposal. Games that you win have a feeling that you piloted every situation correctly. A deck for someone that would like a new sort-of cheap Golgari deck that can roll with the punches and makes every win feel worthwhile.