A new week of Standard means a new "best deck." That's how things have been going recently, and it makes the format quite exciting to play.
Jeskai Lukka is essentially a completely new concept, but one that shines when properly built around. The idea is to play Lukka, Coppercoat Outcast in a deck without any creature spells other than Agent of Treachery. The deck uses other card types to produce creature tokens, which Lukka, Coppercoat Outcast can turn into Agent of Treachery.
This past weekend we had another weekly MagicFest, which right now are the most competitive events you can possibly play in, with tons of very talented players. I ended up bubbling the Top 8 and finishing ninth with my version of Jeskai Lukka, but there were still three copies of Jeskai Lukka in Top 8. Oliver Tiu ended up winning the tournament with his version of the deck.
Since Jeskai Lukka is such a new deck, there isn't really one stock build of the archetype yet. This is especially true because the deck plays Yorion as its companion, which makes deck building even more challenging.
Lukka, Coppercoat Outcast - This is the card the deck is built around, so you should never have less than four copies in the deck, even after sideboarding.
Teferi, Time Raveler - Teferi is another card that never gets cut from the deck. It happens to be especially good here because you have many enchantments to go alongside Yorion, Sky Nomad and Agent of Treachery that love getting bounced for value. Teferi is one of those cards that is going to be strong regardless of what the matchup is.
Narset, Parter of Veils - I sideboard out Narset quite often against aggro decks, but I think you definitely want to be playing this card.
Elspeth Conquers Death - This is another card that gets sideboarded out often, specifically versus Lurrus and cycling decks. While it's bad versus some decks, it's excellent against midrange strategies, of which there are many in Standard. This is one of the enchantments that pairs very well with Yorion, Sky Nomad because you can blink it for more value, or even return your Yorion if it is in the graveyard when Elspeth Conquers Death reaches the third chapter.
Fires of Invention - I have seen versions of the deck that don't play Fires, and that is a mistake. The card provides such an amazing amount of power to the deck.
Omen of the Sea/Omen of the Sun - People realize Omen of the Sea is a must-play all the time, though I have gotten some questions regarding Omen of the Sun. This is one of your strongest cards against aggro decks, and right now aggro is a large enough portion of the metagame to justify its inclusion. Keep in mind it's a token maker that fuels Lukka, Coppercoat Outcast.
Shark Typhoon - This is one of the breakout cards in Ikoria, and works perfectly in a deck that is looking to generate tokens. Shark Typhoon is also great with a Fires of Invention in play, as cycling it allows you to do something with your mana without casting a spell.
The Birth of Meletis - I have seen some players trim down on this card, but it really does everything you want the deck to be doing. It's an enchantment that is inexpensive, makes a token, helps you hit land drops, and can even be flickered out with Yorion, Sky Nomad for some more value.
Agent of Treachery - Your only creature spell outside of Yorion, Sky Nomad is a core part of your game plan because of Lukka, Coppercoat Outcast. I recommend only playing three copies, as naturally drawing multiple copies is rough. Flickering Agents with Yorion, Sky Nomad is how you seal up the game.
Yorion, Sky Nomad - Of course, our companion! The deck is built to abuse Yorion as much as possible. The turn you cast Yorion is usually the turn this deck takes control of the game, as there are so many great permanents worth blinking.
Let's compare my decklist with Oliver's. There is quite a bit of overlap.
Shatter the Sky - I'm including Shatter the Sky here not because I think you should cut it, but because there are some lists that have gone down to two copies or even moved them entirely to the sideboard due to it being your worst card in the mirror game one. Still, both Oliver and I play the full four copies, and as long as aggro decks are a reasonable portion of the metagame this is a card you want.
Narset of the Ancient Way - I personally like this card, but most people aren't playing it. It is extremely flexible, gains you life, and is my four-mana value play of choice.
Omen of the Forge - This is another really useful card against aggro decks, but you don't want to go too crazy on them in the maindeck, so I am using it as my ninth two-mana play.
Elspeth, Sun's Nemesis - This is another four-mana value play you can cast the same turn as Fires of Invention. Having an additional token maker is nice, and it can pop back out of the graveyard in later stages of the game. You don't want too many copies of this card, but one is perfectly reasonable.
Mythos of Illuna - This is a card many players had in the early builds of Jeskai Lukka, but notice that Oliver and I are not playing it. The card is often "win-more," as copying something like Agent of Treachery once you already have one in play is often unnecessary. However, you can also copy opposing permanents, which makes it a useful card in the mirror. Right now I'm still not playing any copies, but it means being slightly behind in mirrors.
Lazotep Plating - I haven't tried this card yet, but I have seen it starting to pop up as a one or two-of, and it's probably worth giving a shot.
Manabases with an 80-card deck are tricky, and we are still trying to figure out the correct ratios. I saw early versions of Jeskai Lukka playing up to 39 lands, which was crazy to me. Oliver has 36, though I was perfectly happy with 34. Thirty-four lands is essentially the equivalent of playing 26 lands in a 60-card deck, and simply adding an additional third of a deck. I would play more lands if it weren't for Omen of the Sea and The Birth of Meletis being really effective ways to hit land drops. You can even cycle an early Shark Typhoon if necessary. Thirty-four is my recommended number.
As far as the actual lands you play, I really liked my manabase. Having some Temple of Epiphany, Raugrin Triome and Castle Ardenvale has proven to be a nice mix. My first recommendation is not to play more than three Plains, and also only play three Castle Ardenvale. You want to have more lands that produce multiple colors of mana, not just white mana. Other than having two extra lands, Oliver's mana is quite close to mine.
Before we talk about how to sideboard, it's important to talk about possible sideboard cards.
Mystical Dispute - By popular consensus, this is a four-of in the sideboard.
Legion Warboss - This card was very good for me in the MagicFest, as it gets under countermagic like Dovin's Veto and Mystical Dispute against other blue decks. However, the fact that it makes our Lukka, Coppercoat Outcast activations worse means I'm still not sure if Legion Warboss is worth it. The card is great when you naturally draw it on turn three after sideboard, but you are a bit less likely to have it in an 80-card deck.
Glass Casket - This is my preferred removal spell, as it can deal with a Fox on turn two from the cycling deck, and can exile annoying creatures in Obosh, the Preypiercer and Lurrus of the Dream-Den decks.
Devout Decree - You only want this card in a metagame with lots of Obosh, the Preypiercer and Lurrus of the Dream-Den.
Aether Gust - It's relatively low impact, but still a fine card to have access to.
Dream Trawler - Against cycling decks getting Dream Trawler is better than Agent of Treachery, so right now I'm playing Dream Trawler.
Deafening Clarion - if you want more sweepers after Shatter the Sky this is good, but right now it seems mostly unnecessary.
Dovin's Veto - At a certain point you have too much countermagic in the same deck as Fires of Invention, and this might be the line.
The important part about sideboarding is having a basket of cards that come in against control/midrange, and another basket that come in against aggro. I want to talk about what cards to take out in general rather than going through individual matchups. This will be helpful in the long term, as the metagame continues evolving.
Against Midrange/Control: Cut your removal, like Shatter the Sky and Omen of the Forgge, followed by a couple Omen of the Sun and one The Birth of Meletis if there are additional cards you still want to bring in.
Against Aggro: Cut Elspeth Conquers Death and Agent of Treachery against Lurrus of the Dream-Den decks so that you can bring in Dream Trawler. Narset, Parter of Veils is also pretty bad against aggressive decks as well, so that gets cut against Obosh, the Preypiercer instead of Elspeth Conquers Death which is actually quite good there. You can also look to shave on your flex slots.
It would be foolish of me to provide an exact 95-card decklist right now, as my opinions on the exact last few slots are constantly changing based on the metagame. However, if you are looking to pick up and try this deck, I would recommend something very close to my list from the last MagicFest.
The deck is tough to play, so don't be surprised if you run into some difficult spots!