There are now 2 elements to this deck. *Edit*
Element #1: Jank Synergy
The main portion is the ETB synergy of Hunted Phantasm and Trespasser's Curse. As soon as Phantasm enters, the opponent will lose 5 life, and you will gain 5 life when they receive the 5 goblins. The Hunted Phantasm swings for 4 dmg unblocked, and if you drop a Saheeli Planeswalker the next turn, you can duplicate, trade 5 life again, then swing with TWO unblockable 4/6's. In a perfect world this is a turn 4 win.
It is not a perfect world.
Since this deck requires some setup to get the synergy going, the other two elements are the supports. We need to be able to dig for our synergy as well as defend ourselves.
If you have Turn 1 Illness in the Ranks, try to always play it first so you don't have to worry later, unless you are up against very aggressive aggro.
Forbidden Orchard also synergies with Curse, getting you some more damage in for a faster win.
Hunted Dragon is a big threat, and doesn't die to Fatal Push. White Removal still hits it, but at least you can get 3 triggers of curse in on your turn. And if they don't remove it, it can swing for the win on turn 5 if you're missing that last 9 health of the opponent. (3 from ETB trigger, and 6 from flying haste). Hunted Horror doesn't seem to fit in this deck because of the double black. Sideboardable?
Element #2: Control and Dig.
Play burn spells against creatures, keep the field leveled as long as you can with Bolts, Magma Jet and Pyroclasms.
Play Counters and Hand-Thief spells to stall even more. Inquisition of Kozelik, Remand and Condescend are used to keep us at a certain tempo.
Most of the spells are added to give use either Scry or Draw to sift through our deck. Our combo is centered around 2 cards with only 4 copies of each, so we need to get to it. Jet, Condescend, Remand, Serum Visions and even Saheeli, help us to move cards out of the way. Considering Electrolyze instead of Magma Jet, but Jet wins for now for cheaper CMC. Also considering Rift Bolt or Chain Lightning for more burn.
Element #3 (Deleted, not enough synergy): Defensive alternate Win-Con.
Soul-scar mage seems to be fairly undervalued in the meta, and works hand in hand with Necroskitter. Necroskitter returns opponents creatures under your control when they die with a -1-1 counter on them.
If someone puts out a 5/5 monster, we can block with soul-scar mage, bolt the creature, then the 5/5 (who is reduced to a 2/2 before combat damage) is killed by the prowess triggered Soul-Scar Mage.
Also, Soul-Scar only targets opponents creatures with the -1-1 counters, so a pyroclasm would trigger prowess, deal 2 dmg to all, reduce enemy creatures by 2, and Soul-Scar would live. Damage is removed before prowess at end of turn.
Also, if you bolt a smaller creature for 3 dmg while Soul-Scar and Nectroskitter are on the field, then that creature would return to the battlefield under your control from both triggers.
With the Burn and Soul-Scar, you should be able to reduce how much dmg you take per turn, and survive until you can trade 5 life and stabilize. If they remove Soul-Scar, that's fine, Lightning bolt and Pyroclasm still hit most creatures in the meta.
If you focus the synergy of soul-scar and skitter, you can get your opponents to focus the wrong synergy, allowing you to fit in the curse and the phantasm as an afterthought.
(going to remove 2X illness for one more necroskitter and a single blazing volley)
The Side Board:
Blackmail - Budget Thoughtseize that can target anything, helps to remove non-basic lands vs Eldrazi, large threats like Ulamog or Karn. Or helps take out their Paths and Fatal Pushes, or Solemnities or any win-con item from Ad Nauseum, etc.
Extirpate: Budget Surgical Extraction. Stops Solemnity combos, abzan grave shenanigans, and kills potent cards we struggled to fight earlier.
Swan Song: More defense against creature hate and Solemnity and Mill (if Fraying Sanity becomes a thing) Consider playing Mindbreak Trap to kill combos as well.
Ceremonious Rejection: Helps vs Eldrazi and Affinity.
Liliana of the Veil: Sac a creature is strong vs hexproof and indestructible. Discard feature lets you thin the hand of control players as well.
Graftdiggers Cage: More stopping of Abzan and Solemnity combos (Kitchen Finks and Geralf's Messenger combo infinitely with Solemnity)
Rakdos Charm: Hate on Artifacts, Hate on Graveyards, and if you don't have illness in the ranks out, can allow you to get 5+ more damage in after Hunted Phantasm Resolves.
Crumble to Dust: Only 2 of because of mana cost. May replace with Ghostquarter, but I'm worried that would mess up our land base. With the scry's just make sure you can get enough mana to cast on turn 4 vs Urza Tron Eldrazi, or Eldrazi Temple or Cavern of Souls. It would maybe work against Valukut Scapeshift Decks if you can stall long enough.
Any help to make this deck better would be great. I didn't put Blood Artist or Seeker in this deck for now, because they die to pyroclasm, and even though they do massive work, I'd rather just have two Trespasser's Curse out. Also Thinking about using Transmute cards to help tutor up the win con's faster.
Another deck I have is a bit thicker Creature-Wise than this one, check out my Decks, if interested, in the description above.
Weaknesses: Blood Moon, Solemnity, bit temp creatures. Swan song, Inq of K, and Blackmail to watch for some of these.
Win/Loss Results: (Describes running tested modern matches and changes to the deck after the fact)
Budget Bant Eldrazi: Win 2/0
Abzan Tarmagoyf: Loss 1/2 - See Goblin Chocolate Rain: First Cut
Affinity: Loss 0/2 - Added Playset of Pyroclasm after this match.
Dredge, bloodghast, amalgim: loss 1/2. Close and got beat at topdeck. Need better dig/board control?
U/W Taxes/Flicker/Aggro: Loss 1/2. Game 1 dead hands, game 2 win, game 3 dead hand. Dies to fast decks? Needs mass bounce?
CoCo Exert, Intruder Alarm Infinite combo:game 1, all necroskitter and soul-scar. Got synergy off and stole creatures, but combo game 1000 tokens to opp. Game 2, win, Game 3, win. Soul-scar and Necroskitter should come out, more synergy boost.
Abzan Lili/Goyf: 0/2 losing cards in hand wrecks my digging. Abrupt decay wrecks my synergy. Play bounce or hexproof items for protection/control. Echoing truths? Beat deck in friendly match.
Abzan Lili/Goyf: 1/2 needed to push the synergy a bit more, or have some burn in hand. SB removed graveyard more than enough, but lili discards kept them alive.