MTG Salvation

Usually, this is 3-4 Gifts Ungiven, 2 Past in Flames, and some number of cards to find Gifts.
Gifts Ungiven: This is the central card of the strategy, and is critical to the entire deck.
Past in Flames: This is your finisher. It's very strong both in the early game as a powerful combo engine and in the late game, where it can represent dominating card advantage. Resolving one usually means that the game is over.
Merchant Scroll: This card is a very strong tutor in this deck, capable of searching out a Gifts Ungiven, cheap countermagic to protect a bomb, or various answers to other decks or hate cards such as Repeal, Trickbind, and Hurkyl's Recall. Running it as your extra engine piece makes it way easier to resolve an early Gifts and makes sideboarding a lot easier, but can weaken your countermagic.
Peer Through Depths: The main strengths here are the ability to splice a Desperate Ritual onto it to generate mana and to cast it on the endstep, making your rituals that much stronger. However, it doesn't have the same reliability as Merchant Scroll.
Mind Spring/Blue Sun's Zenith/Invoke the Firemind: I think the synergy between draw-X spells and a deck full of rituals and filter lands should be obvious. I was underwhelmed, but they're worth examining, for certain.
Mystical Teachings: This card has natural synergy with the deck, both searching for Gifts and providing a way to optimise Gifts piles. While you run the risk of being top heavy, it's definitely a good supplement. Additionally, it allows for a painless transformative sideboard plan, involving Teferi, Mage of Zhalfir and whatever fatty you like most.
Muddle the Mixture: This card is an incredibly versatile tool, both protecting your combo in the late game and tutoring for the critical Grapeshot. It also dramatically expands your bullet suite, since you can use Merchant Scroll to tutor for it and then transmute it for a ritual, additional bullets, almost anything.

this should be fairly standard across all gifts Lists.
Seething Song: this is BANNED.
Desperate Ritual/Pyretic Ritual: These are important to being able to power out early Gifts, combo turns, and having mana to get through soft counters like Spell Pierce. Desperate Ritual's splice effect can be more relevant than you think.
Manamorphose: Blue mana for the kill and for Gifts is at a premium on combo turns and throughout the game. The fact that it cantrips and is card advantage with Past in Flames is a major bonus.
Mana Seism: This is an untested possibility. It would be very strong in the late game, but has basically no synergy with Past in Flames and is very all-in on comboing them out when you play it.
Increasing Vengeance: I almost never go without this card. It doesn't seem strong on the face of it, but when you realize that it costs 2 to copy something twice when flashbacked off Past in Flames, it becomes crucial to comboing out in a timely fashion. Imagine copying Seething Song twice with it. Or Gifts Ungiven. It's just incredibly strong in this deck.
Channel the Suns: Now that Song has been banned, most ritual gifts decks are splashing green for Channel the Suns and a couple of other cards. It does a decent Seething Song impression, though it's harder to go off with.

Grapeshot: This is the best kill card when combined with Remand. Storm makes it almost uncounterable, while Remand makes it much easier to reach the necessary storm to kill them. Because of the tutor power of the deck, you only need to run 1.
Empty the Warrens: This was critical to earlier versions, but in this age post-Dark Ascension, it's just unecessary.
Martial Coup: This one's greatest strength is in cases where a combo is unreliable, for instance, when the opponent has Trickbind or is exerting pressure. With Martial Coup, you can create hybrid Gifts Piles where you can get defensive cards to keep you alive, and the requisite spells to Martial Coup for a giant threat and board wipe. It's definitely worth considering if you're going to try to build the deck.
Unburial Rites/Iona, Shield of Emeria/Inkwell Leviathan/Griselbrand: What would a gifts deck be without this package? You have a fair choice of fatties to get. I know I've used Elesh Norn, Myr Battlesphere, Inkwell Leviathan and even Sundering Titan before, but now I believe that the best option is Griselbrand. You may prefer Iona, your mileage may vary, but I believe Griselbrand is the best option.

There's a lot of variety in choices available, but you want to have a fair number of them. Also, they have to be cheap. No Cryptic Commands here.
Remand: You have to have at least one, possibly more. It's critical to the Grapeshot Kill, and is a very strong spell in and of itself.
Spell Pierce: Most of the threats your opponent might have that you can't just ignore are noncreature spells. Liliana of the Veil, other counterspells, Rule of Law, and so on. Spell Pierce is very strong in all of these situations.
Spell Snare: This is just a very strong counterspell. You don't want all that many of them, though, as they get worse in multiples very quickly.
Dispel: A lot of what applies to Spell Pierce applies here, but the prevalence of cards like Liliana make Spell Pierce a lot stronger, in my opinion.
Pact of Negation: this can make comboing out much easier, and is easy to include as a singleton and fetch with Gifts or Merchant Scroll.

These are the cards that really make the deck yours. They will vary depending on your meta and your own personal play style, but they are largely defensive spells that allow you to use Gifts to stabilize as well as combo the opponent out.
Increasing Vengeance: Run 1-2 as a Gifts Target. No, really. There is no better card for your combo turn. Flashing it back for RR after a Past in flames and targeting Seething Song is just so strong. It's what makes the deck consistent enough to get a Grapeshot kill on turn 4. There are builds that run 2. I run 1, personally, but it all depends on how many times you expect to use it in a combo turn.
Volcanic Fallout: This is a fairly new discovery, and a very strong one. The current modern metagame seems to be flooded with a lot of Delver decks, aggro decks like Affinity and Boros, and basically decks relying on a lot of small creatures that either become huge threats, are very disruptive, or provide card advantage. Volcanic Fallout not only can wipe the board, but also can kill Planeswalkers at low loyalty, make it easier to combo out if they have lifegain (every stray shock can matter), can be cast at instant speed to kill Inkmoth Nexus or other manlands, and can't be countered.
Slagstorm: See above mostly, though it's not quite as strong.
Earthquake: I didn't like this at first, but now I'm warming up to it. One of the most dangerous cards against you is Liliana of the Veil, and much of the Jund matchup is about keeping her off the table. Earthquake can do that, and wipe the board of larger creatures, and synergises with rituals, and can make it easier to combo out.
Engineered Explosives: This is just a very strong, efficient answer card, well worth the inclusion.
Snapcaster Mage/Noxious Revival: These 2 basically can fill the same slot of making Gifts piles stronger. I've never felt the need for them, but they're worth considering.
Repeal: You'll rarely Gifts for this, but it's worth noting that this can be tutored for with Merchant Scroll, cantrips, and can beat a lot of hate.
Timely Reinforcements: This can completely nullify an opponent's board pressure, while gaining you a bunch of life. Usually it will buy you 2 turns, which most opponents simply can't beat.
Gigadrowse: Excellent versus control decks, and can be tutored for with Merchant Scroll.
Life from the Loam: A few other friends of mine are working on similar lists. One splashes green for Life from the Loam and some sweet sideboard tech (Tarmogoyf, Ancient Grudge, you get the idea). I wouldn't go that route, but it is something to factor into your decision making process.
Cyclonic Rift: This card does a LOT for you, acting as both a way to bounce a problematic hate spell and as a late-game bomb that can potentially end the game on its own. Chances are, if you don't have one of these in your main or sideboard, you're doing something wrong.
Mizzium Mortars: Similar to Cyclonic Rift, this card serves multiple purposes, acting as both removal early and as a board wipe in several matchups. It's also tutorable with Muddle the Mixture.

You want to play more lands than other storm decks, but less than other control decks. Somewhere between 19 and 22.
Fetchlands/Shocklands: If you have them, run them. It's just the most stable mana base, and since you don't tap out on your turn too often, they can be quite strong. You pretty much have to tune them yourself to your deck's mana needs, though Scalding Tarn and Steam Vents are a good start.
Cascade Bluffs: This card can be crucial to getting the necessary blue mana for the deck to go off. I'd run 4.
Calciform Pools/other storage lands: I only just found out about them again, and they're very strong in the deck. The ability to continuously build up mana and to convert red mana into blue are both very important. You have to be very careful how you tap them, though, and how many counters you remove. Remember that you basically can't go off if you don't have blue mana afterwards.
Halimar Depths: I've just started testing this, and it's turned out to be deceptively strong. You have a LOT of shuffle effects, which makes this a lot stronger. I'm not currently running any, but it's definitely an option.
Desolate Lighthouse: This deck is fairly prone to flooding, and wants to draw one of a fairly small number of absolutely massive game-ending bomb spells. This card digs into your deck for them, provides a good mana sink, and fills your graveyard all at once. You definitely want to pack at least on as a Gifts target.
Basics: You really don't need any mountains, as the only nonbasic land hate you have to worry about in this deck is Blood Moon, which turns all nonbasics into... mountains. I'd run as many basic islands as possible, though. It can be very important.

Remember the key to this deck? Play to your strengths? Think of the matchup that way, and you should win. You'll be tempted to throw huge bombs onto the stack and try to overwhelm your twin opponent. After all, your deck is built to be fast and explosive. DON'T DO IT. Twin is a very strong deck. It has a 2-card infinite combo with plenty of redundancy. It is built to win counterwars, usually with maindeck Dispels. It's just as fast as you are, maybe a bit faster. So, how do you beat it? Play do your strengths. Figure out what you have that Twin doesn't, and make the game about that. In this case, it's Card Advantage. Twin usually has no Card Advantage mechanism, preferring to rely on dig and end the game before card advantage becomes necessary. You, however, are designed to generate fast early card advantage with Gifts Ungiven, and have a very strong draw engine available. Try to grind the game out with defensive Gifts piles, and you'll be able to answer their threats and just run them out of cards while you continue to develop your hand and board, until you finally strike the death blow with Past in Flames. Sideboard: -1 Earthquake, -1 Engineered Explosives, -2 Volcanic Fallout, -2 Spell Snare, -1 Repeal, -1 Martial Coup, +3 Combust, +1 Flashfreeze, +1 Wipe Away, +1 Rites, +1 Iona.

The critical card here is Liliana of the Veil. Keep it off the table, and chances are you’re going to win. Fail to do so, and it can be very difficult to get back in the game. Don’t be afraid to scroll for a counterspell. That’s an important play to be able to make here. Sideboarding: -1 Pyretic Ritual, -1 Remand, -1 Martial Coup, -1 Volcanic Fallout, -2 Spell Pierce, +2 Flashfreeze, +1 Unburial Rites, +1 Iona. A bit of explanation: You only rarely want to get an early Gifts out in this matchup, so Pyretic ritual is much less important than having a critical mass of good countermagic.

This matchup is pretty easy. They have no way of reloading, and Volcanic Fallout makes it easy to catch out their Nexi as well. Usually, all they have to side in is Ethersworn Canonist, which is absolutely useless against cards like Repeal, Hurkyl’s Recall, and your mass removal spells. They might side in Blood Moon, but you can play around it and it’s not too hard to keep it off the table if you’re worried. Sideboarding: -3 Spell Pierce, -1 Repeal, +2 Hurkyl’s Recall, +2 Geistflame.

I haven't played this matchup very much, so I don't know much about it. I haven't done well, but that may be because I don't know which cards to counter. I don't have a solid sideboard plan, too. Any help with this would be appreciated.

this matchup is a beating for them, plain and simple. They have no stack interaction and mainly rely on controlling the board, a strategy which doesn't work against a deck full of counterspells that can win off the stack alone. They have so many dead cards, it's hilarious. Their only hope in game 1 is to get a very strong early martyr and padding their life total so you just fizzle, and even that doesn't work too well. Then they overload on Rule of Law effects, and you side in Rites/Iona and lock them out. Cake. Sideboarding: -1 Earthquake, -2 Volcanic Fallout, +1 Unburial Rites, +1 Iona, +1 Wipe Away.

This is a very good matchup. While they have quite a bit of reach, you can easily force them to overextend, then crush them with mass removal. Don't be afraid to race. They have no way to stop you, so if you have a fast draw, you can kill them, and they often take a lot of damage off fetches and duals. Sideboarding: -3 Spell Pierce, +2 Geistflame, +1 Flashfreeze

This is like the opposite of twin. Tron is a very strong deck. It has late game trump over every other deck in modern, in the form of Emrakul. It has its own draw engine, one just as strong as yours (Gifts/Thirst). It has a superior mana engine in the late game. So, what do you have that Tron doesn't? You're much better at exploding early. You have 7 Gifts to their 2-4. You have more and better early countermagic, while they generally have to tap out. Play aggressively, dropping huge bombs onto the stack every turn, and you will win. Knowing when to cast your tutors can be critical, and slowrolling is definitely helpful. Try to bait out any countermagic they might have, or use the first Merchant Scroll to get a counterspell, so you can resolve your Gifts unimpeded. Sideboarding; -1 Earthquake, -2 Volcanic Fallout, -1 Martial Coup, +1 Rites, +1 Iona, +1 Wipe Away, +1 Dispel.

This is a quite strong matchup. Volcanic Fallout is very, very strong against them, and you can pretty effectively grind them out. You do want to win fairly quickly, however, so don't just try to stall out the game. Try to stop their clock, then win as fast as possible. Constructing good Gifts piles is key in this matchup, and can be very hard. Basically, don't be afraid to get an ugly one. I fairly often grab something like this: Past in Flames, Martial Coup, Seething Song, Volcanic Fallout. You want to sculpt your gifts piles so that, rather than presenting an auto-win (usually impossible in this matchup, up to a fairly late game), you instead present a pile where every possible permutation gives you an effective line of play, while setting up for the late game win. Sideboarding: -3 Spell Pierce, +2 Geistflame, +1 Dispel.

This is a really easy matchup. They can only rarely interact on the stack, so you largely have free rein to build up your board position, and your clock isn't much worse than theirs is. Most decks have a bad game 1 against U/R storm, but I think you're actually favored game 1, and you crush them after sideboarding. Sideboarding: -1 Earthquake, -1 Engineered Explosives, -1 Repeal, -2 Volcanic Fallout, -1 Martial Coup, +1 Rites, +1 Iona, +2 Flashfreeze, +1 Spell Snare, +1 Trickbind.

This is a very easy matchup. Basically, you're the same strategy, but where you plan on comboing your opponent out in a single turn, they plan on killing you with 1/1 fliers. Yeah. You can outdraw them, are much more broken than they are, and have a trump card for most situations that could come up, Volcanic Fallout. I'm not going to give a sideboard strategy for my list, because the list is outdated and the sideboard has changed. I will update all of this when I update the list.