This is a tricky deck to play (comments are provided below). It also is good in multiplayer; I consider this deck to not be a "casual play" deck (it is pretty competitive and many opponents may not like playing against it).

A) There are plenty of mana ramp sources (artifacts). Get Zur out and find an enchantment each turn in this order: 1 Necropotence, 2 Font of Agonies, 3 Underworld Dreams, 4 Profane Procession; pick Righteous Aura or Greater Realm of Preservation as needed. Necro should be out by turn 4 if possible.

B) Spellbook, Finale of Revelation, Reliquary Tower, Folio of Fancies, Library of Leng, or Nezahal provide no maximum hand size or no discard phase. Paired with Ivory Tower, you should Necro for 15-20 or so cards. There is no need to discard any at the end of turn with one of the above cards in play and, with Ivory Tower, you will gain 13 or more life each turn. Pulling 20 cards should provide a few pieces (if not one complete set) of several 2-3 card combos within the deck. Folio of Fancies can be used to supplement card draw (from Necro). 

C) There are several tutors in the deck to pull out the remaining combo pieces: Demonic Tutor, Diabolic Tutor, Mastermind's Acquisition, and Merchant Scroll. Narset's Reversal can be used to "duplicate" one of the tutor spells (which is then returned to hand); Mission Briefing can be used to recast a tutor spell from the graveyard (only before you play Necro, as all discards are exiled with Necro in play). One tutor should be used to find Ivory Tower (if you do not pull it with the Necro draw) in order to gain massive amounts of life--you will effectively be able to just accept most damage with this combo, so no need to block attacks (Necropotence + no maximum hand size + Ivory Tower). Fill in one or more combos to lock down or win by turn 5 or 6.

D) The combos are as follows:
1)  Atemsis, All-Seeing (with the number of cards in hand from Necro) is almost always a one hit win (or one hit opponent loses the game). Other big creatures that can be dropped are Nezahal, Primal Tide and Zetalpa, Primal Dawn; use Vesuvan Doppelganger to make copies of these. With the amount of cards in hand from Necro, Nezahal should be unstoppable (just discard to bounce it).

2) Famished Paladin + Spirit Link (which Zur can fetch) + Sorcerer's Wand (automatic win). Equip the wand to the paladin and Spirit Link it; tap Paladin to do 1 damage to opponent and gain 1 life; untap Paladin and repeat for how ever much damage is required to kill opponent or clear the board.

3) Jace, Wielder of Mysteries + Demonic Consultation + Necropotence (automatic win). Play Jace and then use Demonic Consultation to search your library for a card that is not in there (like Black Lotus). This will completely mill your library away, then Necro for 1 to win (or use Folio or wait until next draw phase). Alternatively, with Jace out, if you have enough life you can just Necro for the win (draw all remaining cards in library). 

4) Karn, the Great Creator + Mycosynth Lattice (board lock). Karn prevents opponents from using activated abilities of artifacts and Mycosynth Lattice turns all permanents and spells in play into artifacts (including lands). Therefore, opponents are no longer able to cast any new spells (they become artifacts as they enter play) or tap lands (as they also are artifacts); opponents can still attack and block with creatures on the battlefield, but they cannot use any creature abilities. Karn +1 ability also can be used to destroy opponent lands (artifact lands become 0/0 creatures).

5) Blink of an Eye or Callous Dismissal + Mirari Conjecture (along with Narset's Reversal) can be used to recycle sorcery spells like tutors or board wipes every turn. Play board wipe/tutor, play Mirari conjecture; on saga turn two return board wipe/tutor to hand from graveyard, play blink or dismissal to return Mirari Conjecture to hand, then replay it and return blink or dismissal to hand (then the tutor or board clear can be played every turn or every other turn as above). The best board wipe to use is Time Wipe, as it allows you to bounce a creature back into your hand (e.g., Zur). For this combo note that you should return Necropotence to your hand first, as all cards that go to the graveyard are exiled. Alternatively, this combo can be used if an opponent manages to remove Necropotence from play.

E) Board wipes: Day of Judgment, Ravnica at War, Ritual of Soot , Time Wipe, and Flood of Tears (to remove tokens).

F) Removal: Mortify, Swords to Plowshares, Settle the Score, Hieromancer's Cage (can be replaced by Prison Realm or other 3 mana casting cost enchantment that Zur can find). Font of Agonies will get many counters from Necropotence and can be used to remove creatures; Profane Procession also can be used to exile creatures. Abu Ja'far is better than deathtouch for removing problem non-flying creatures. Pithing Needle can be used against opponent commander. Control Magic can be used to take control of a strong creature.

G) Protection: Angel of Grace and Dawn Charm can be used to survive large attacks from many creatures. Angel of Grace can extend life to 10 from the graveyard. Greater Realm of Preservation will reduce all damage from a black or red source to 0 for 1 colorless mana; Righteous Aura can be used to reduce all damage from any source to 0 for 1 white mana and 2 life. The Wanderer prevents non-combat damage. 

H) Use counterspells primarily to protect Necropotence and other permanents that prevent you from discarding; also to block bomb drops by opponents or slow them down: Absorb, Cancel, Counterspell, Dovin's Veto, Mana Drain, Negate, Power Sink, and Syncopate.

I) Kaya, Orzhov Usurper, Smothering Tithe, and Underworld Dreams are solid miltiplayer cards and really the focus is to make them targets (as opposed to the other important enchantments/permanents in the deck). Smothering Tithe can be used for mana and Underworld Dreams can be used to cause a little bit of recurrent damage. Kaya can remove small creatures to slow opponents down or remove key cards from graveyards--they are otherwise distractions to the real combos.
--RED_GREEN