A fairly run-of-the-mill Gifts Storm deck for Modern, based heavily on Caleb Scherer's list.
I'm planning on adding a one-of Noxious Revival once I can get my hands on one, and moving to a fetchless manabase centered around Steam Vents, Spirebluff Canal, and Shivan Reef once I can pick up two more Vents.
I am also in the process of changing the sideboard to deal with my LGS' metagame (at the last Modern event of 16 players there were 3 Ponza decks XO )
Deck Record
All matches played: 6-7
Matchups:
2-0 vs. -based Control
1-1 vs. Mardu Pyromancer
1-0 vs. Hollow One
0-1 vs. Affinity
0-1 vs. Eldrazi
0-1 vs. Land Destruction (Ponza)
0-1 vs. Martyr Proc
1-0 vs. Tron
0-1 vs. Scapeshift
1-0 vs. Grixis Control
0-1 vs. Artifacts
Explanations of the categories
Lands (18)
4 Wooded Foothills
3 Flooded Strand
4 Spirebluff Canal
2 Steam Vents
1 Shivan Reef
3 Island
1 Mountain
I have included 18 lands, including 7 fetch lands and 2 shocks. 18 is a good number for the Storm deck, because we can often win the game with 2-4. Optimally I would have Scalding Tarn in place of Wooded Foothills, but yo boi is broke AF right now. The eventual goal is to move to manabase that features 4 each of Spirebluff Canal, Steam Vents, and Shivan Reef, but I need to get my hands on 2 more Steam Vents to make that happen.
Manadorks (7)
4 Baral, Chief of Compliance
3 Goblin Electromancer
These guys are key to making this deck hum along nicely. When you're trying to cast 15-20 spells in one turn to Grapeshot your opponent into oblivion, things are made much easier when every spell you cast costs less. Both Baral and Electromancer turn Pyretic Ritual and Desperate Ritual into de facto Dark Rituals. They also make Manamorphose completely busted, allowing me to net 1 mana and draw a card. The discount that they give to Past in Flames or Gifts Ungiven can also be potent - sometimes it's worth jamming a manadork on Turn 2 if you're holding a Gifts because Turn 3 gifts often secures a Turn 4 victory.
There are more Barals than Goblins because Baral is better in every relevant situation. The extra point of toughness can help us block some early aggression from low-to-the ground decks, and the looting ability can help us gain a bit of extra advantage when we use Remand.
Rituals (12)
4 Desperate Ritual
4 Pyretic Ritual
4 Manamorphose
The core of any storm strategy are ritual cards, i.e., instant/sorcery cards that gain you mana each time you play them. Not only do these cards add to the storm count that you need to eventually win with Grapeshot or Empty the Warrens, but they give you more mana which you can use to cast more spells to keep the chain going. Although Manamorphose technically isn't a ritual, it will usually function like one, netting us one mana thanks to the effect of Baral, Chief of Compliance or Goblin Electromancer. Past iterations of Modern Storm have used even more potent rituals like Seething Song and Rite of Flame that have since been banned - but the deck works almost as well without them.
Cantrips (10)
4 Serum Visions
4 Sleight of Hand
2 Opt
The other key part of a Storm deck's "going off" turn are cantrips, cards that cost 1 mana, draw a card, and have some other minor effect. These cards combine with rituals to help us cast as many spells as possible in one turn - make mana, draw cards, make mana, draw cards, ad infinitum. Serum Visions is our best card here - being able to send two pesky lands to the bottom of the deck when you're close to fizzling out can be crucial. That being said, Sleight of Hand can also be better sometimes, as it's the only cantrip we have that has the ability to give us a card that's two cards deep instead of one. Opt rounds out our trio of cantrips. This is another section of the deck that has been the target of several bans - Ponder and Preordain were struck from the format in the early days of Modern, and the powerhouse Gitaxian Probe more recently, but the cantrips we have now work well enough to keep the deck viable.
Critical Mass (6)
4 Gifts Ungiven
2 Past in Flames
There are hundreds, if not thousands, of potential possible routes to putting 20 copies of Grapeshot on the stack and killing your opponent with this deck. It's not usually any specific combo of two or three or four cards that lets you know you're going to win, it's usually reaching a "critical mass" of spells that will allow you to keep going and add to your storm count. Usually, you can make a good attempt at going off if you have 1 mana dork, 1 "Critical Mass" card, and a couple of rituals/cantrips. The win condition is optional seeing as we have 3 in the deck and typically you will draw enough cards to see it on the final turn. Gifts Ungiven allows us to tutor for 4 unique cards and ask our opponent which ones go into our hand and which ones go into our graveyard. The problem for them is, with our deck it's a false choice, as Past in Flames allows us to flash every instant and sorcery back from our graveyard. Unless the opponent has some sort of graveyard hate on the battlefield like Grafdigger's Cage or Tormod's Crypt (there are many more), Gifts Ungiven essentially reads : tutor for four unique cards and put all of them into your hand. That's very powerful by Modern standards. Typically with Gifts Ungiven you want to pick the following four cards: Pyretic Ritual, Desperate Ritual, Manamorphose, Past in Flames. Getting this combination of cards will usually win you the game regardless of where your opponent decides to put which cards. Another helpful use of Gifts Ungiven in post-board games can be to tutor up specific hate cards - like Shattering Spree or Gigadrowse - to deal with something annoying before going off. Even before sideboarding it can help us find Repeal, Unsubstantiate or Remand if they're necessary to deal with something.
Past in Flames is our other key "Critical Mass" card. Although it's possible to win without it, it's drastically more difficult. This allows us to cast everything twice, essentially, giving extra life to cards we've already cast, giving us more mana and more card draw. It also allows us to go Grapeshot for 9, Past in Flames, Grapeshot for 11 to kill someone more quickly and more easily.
Win Conditions (3)
3 Grapeshot
This one's pretty self-explanatory. In order to win with a Storm deck, we need some sort of card that can kill the opponent if we have enough copies. Tendrils of Agony isn't available to us in Modern, so the next best thing is its weaker, redder cousin, Grapeshot. The most direct route to killing someone is casting 19 spells and then making the 20th Grapeshot, but Past in Flames can make it so we really only need to cast 8-9 spells at the most, flashing back Grapeshot for the final 10-11 points of damage. In unlikely but not unheard-of situations, we will also take advantage of Remand or Unsubstantiate to bounce Grapeshot back to our hand to get a similar effect (the copies will remain on the stack even when the original spell is returned to the owner's hand). The Storm strategy is wonderfully resilient to countermagic as well - a traditional counterspell can only counter one copy of Grapeshot because all the copies are placed onto the stack immediately when you cast the original. The only possible out someone could have once Grapeshot is on the stack is something along the lines of Counterflux or Mindbreak Trap. One final note - the card can be used as removal in odd situations where we're low on life and need to chain a few spells together to grapeshot for 4-8 points to clear a board and buy us an extra turn or two.
Interaction (4)
2 Remand
1 Unsubstantiate
1 Repeal
We can't afford to dedicate too many spots in this deck to things other than storming out our opponent, but these useful cards have found their way in over the last few years. Remand is helpful to just say "no" to something that could screw us over. Although it's not the best counterspell, it can often be enough in the early game to cast aside one piece of interaction from our opponent and then start the storm chain. As mentioned above, it can also be used to bounce our own Grapeshot back to our hand to double our storm count. Repeal finds itself here as an answer to difficult mainboard cards that pop up from time to time, like Chalice of the Void from particularly annoying Tron players, or Thalia, Guardian of Thraben in Humans. Unsubstantiate straddles a really nifty line between the two, being incredibly useful as a Remand without the draw in some situations and a less flexible Repeal in others.