Recently, I built a Gifts Storm deck and I was searching for a guide of how to play Storm. However, I couldn't find an especially good one, so I decided to make my own.
The decklist with the sideboard can be found here: https://www.mtgvault.com/jxue16/decks/modern-storm/
The Gameplan
The gameplan is relatively simple for game one.
1. Play a Baral/Goblin Electromancer on turn two. (Turn three if you expect opponent to have removal, holding up mana for counterspell)
2. Generate a total of 6 mana. (With lands and rituals)
3. Use 3 mana to play Gifts Ungiven for Desperate Ritual, Pyretic Ritual, Manamorphose, and Past in Flames
4. Generate more mana.
5. Play past in flames.
6. Play all rituals
7. Play Gifts Ungiven again for Gifts Ungiven, Manamorphose, Desperate Ritual, and Grapeshot
8. Play more rituals
9. Get storm count high enough to grapeshot.
10. Repeat steps 6-9 enough to win.
However, after game one, the other deck will sideboard in much hate. This includes Leyline of Sanctity (prevents targetting for Gifts Ungiven), Rule of Law, Trinisphere, Thorn of Amythest, Eidolon of Rhetoric (etc.).
If we assume they will have Leyline of Sanctity or other 'give yourself hexproof' cards, we will take out a few copies of Gifts Ungiven for Pieces of the Puzzle. We will also add in bounce cards and counterspells.
If we expect an Eidolon of Rhetoric/Ethersworn Canonist/Eidolon of the Great Revel, we will sideboard in cards like Izzet Charm and Flame Slash.
If they're running Tron/Valakut, we bring in Blood Moon. We also bring in Shattering Spree, as their only answers to Storm are typically artifacts. We will also bring in Shattering Spree against Affinity.
Empty the Warrens is a last resort, for we don't ever want to use it. We only use it when we expect that it will be near impossible to win with Grapeshot. However, Empty can be easily covered by wraths and is very much expected.
Counterspells are brought in against counterspell decks, as is Gigadrowse, as it basically turns into 'spend 4-5 mana: take an extra turn'.
A lot of calculation is needed for storm, usually many turns ahead, as you need to know how much resources you need.
The grapeshot-remand kill also works, where you remand your own Grapeshot to add to the storm count and play it again.
Overall, Gifts Storm is an amazing deck and is very fun to play.
Thanks for Reading.