Pro Tour Rivals of Ixalan is finally here! In my view, Modern is just about the best format there is (perhaps outside of Pai Gow and Judge Tower), and I can't wait to see what tens of thousands of collective testing hours does to the format as it all comes to a head in Bilbao. As I expect it to make a strong appearance this weekend, we're finishing up our investigation into Mardu Pyromancer this week, and then will explore a few other sleepers that might make an impact. Let's get to it!

We've already talked about the broad function of Mardu as a deck, highlighting the importance of its one-mana spells and its ability to grind out games like a champion. Last week, we talked about matchups in general terms, covering aggro to control and everything in between. This week, it's time to finish up by looking at specific sideboard options, and how they stack up against the expected field.

Many of the sideboarding routes that Mardu Pyromancer can take are reasonably straightforward and don't require enormous amounts of explanation – for example, take removal out against creature-light decks, or quicken the clock against linear decks. There are many ways in which to reconfigure post board, but most Mardu decks currently build their sideboard from an all-star lineup of post-board options.

Goblin Rabblemaster

Goblin Rabblemaster is perhaps the most important sideboard card in the deck – it's so important in some matchups that it even sees play in the main deck. For the most part, I suspect this is a mistake, but it's easy to understand why people consider it to be the right thing to do. Rabblemaster is the most straightforward way for Mardu to beat both uninteractive or big mana decks, as it will speed up the clock considerably. If an opponent has no way to deal with G-Rabs, he'll make short work of them, especially when the way has been cleared with early discard spells.

Given the unfavourable nature of big mana matchups especially, it's critical for Mardu to have a way to close games out swiftly. Blood Moon is all very well, but it needs to be combined with meaningful pressure in order to be truly backbreaking. Otherwise, Scapeshift will find their Reclamation Sage and one-shot you, or Tron will just naturally get to seven lands and Karn you. Despite the importance of Rabblemaster, however, I don't think it's a good main deck inclusion as it dies to basically every removal spell ever printed.

Blood Moon

Blood Moon is the other tool Mardu has against the big mana decks in the format, as well as providing excellent value against the greedier mana bases of the format. Any deck that only plays a few basics is always a good target for a Mooning, so don't be afraid to board this in (especially on the play) against decks like Abzan, Jund, Jeskai, and the like. It's also a decent option against White-Blue Control, as it shuts off both Celestial Colonnade and Azcanta, the Sunken Ruin.

Leyline of the Void, Nihil Spellbomb

With Mardu, graveyard hate is a little trickier than in most decks as it simply must be one-sided. Symmetrical graveyard hate like Rest in Peace will hamstring Mardu's game plan just as much as an opponent's, and so for that reason cards like Leyline of the Void and Nihil Spellbomb fit the bill. The jury is still out on which is best – obviously an opening hand with Leyline feels excellent against a deck like Dredge, but when you draw on turn one it you'll feel like the biggest idiot since the guy who put an ejector seat in his helicopter.

Nihil Spellbomb is obviously excellent as it's cheap and replaces itself, but there are plenty of matchups where one-shotting their graveyard isn't sufficient. Nevertheless, I would lean towards the Spellbomb; the fact that it cycles in a pinch means the card will always do something, unlike a Leyline rotting away in hand when you're mana-screwed.

Collective Brutality

An unbelievably versatile card, Collective Brutality plays both sides of the court in being truly excellent against Burn while still serviceable against spell-heavy control (or combo, at a stretch). If you're ever in a situation where you've boarded out extra cards and aren't sure what to bring in, Brutality could be the pick given its utility in almost any situation. It's very difficult to do anything other than trade one-for-one with this card, and that's the name of the game with Mardu.

Engineered Explosives

The emergence of go-wide aggro decks like Five-Color Humans necessitates the inclusion of Engineered Explosives. One-for-one removal isn't spectacular against many decks that flood the board, and Explosives acts as a pseudo-sweeper in these situations. Additionally, it's excellent when up against weird fringe decks like Enchantress or Soul Sisters; generally speaking, its versatility is a nice hedge against opponents looking to perpetrate some silly nonsense.

Wear // Tear, Shattering Spree, Stony Silence

As Affinity is an exceptionally good matchup for Mardu, artifact hate isn't as critically important as usual. There are lists floating around that include Stony Silence, but I think this is overkill. Obviously it's excellent against Lantern Control as well, but they can still win through Stony Silence with cards like Ensnaring Bridge and Tezzeret. Instead, I look to cards like Wear // Tear and Shattering Spree. I like Wear // Tear especially, given its flexibility – it improves the White-Blue Control matchup by tussling with Detention Sphere and an unflipped Search for Azcanta.

Kambal, Consul of Allocation

Kambal plays an important role for Mardu post-board, doing heavy lifting against both Storm and Burn. Against Storm he's essentially an Eidolon of the Great Revel, and against Burn he's essentially the opposite of that. Eidolon of Supreme Chill? I don't know. In any case, this fellow should always be in your 15 given the powerful impact he has on these common matchups.

Other Potential Breakout Decks

Mardu Pyromancer has been putting up stronger and stronger results, and is threatening to become a mainstay of the format in the wake of the Pro Tour. After catching up with various pros about what's to come this weekend, however, Pyromancer isn't the only list I have my eye on (wait 'til you see what Lukas Blohon is playing!). Modern has proven itself to be open to new angles of attack – just look at the ascendancy of Five-Color Humans – and so with that in mind, here are a few other strategies we could see hit the big time over this weekend.

Black-Red Hollow One

Hollow One is a card that is begging to be broken. People have been hard at work trying to break this stony boi since he joined us during Hour of Devastation – so far, however, no dice. There are a squillion ways to discard cards in Modern, however, and each iteration of this list seems only to improve it further. In other words, this deck keeps getting better and better – perhaps it's only a matter of time before it truly breaks through.

Casting a free 4/4 that is Bolt and Push-proof is an excellent way to heap on pressure. This deck is excellent at discarding cards through enablers like Burning Inquiry and Goblin Lore, and gets around the random discard "drawback" in a unique way. The solution is play creatures that are best when in the bin (Bloodghast and Flamewake Phoenix) alongside other threats that reward you for a stocked 'yard (Gurmag Angler and Bedlam Reveler). Who knew Goblin Lore ever threatened to be a Constructed powerhouse?

Red-Green Land Destruction (Ponza)

Have you ever registered four copies of Stone Rain in a Constructed deck? If you've not, you haven't ever really lived – forget swimming with dolphins or whatever, it's all about turn-two Stone Rains. Back that up with Mwonvuli Acid-Moss, Primal Command and Blood Moon, and you've got a stew going. Better yet – it's just about the saltiest stew you're ever going to come across.

At heart, this deck is essentially a ramp deck, cruising at top speed towards cards like Stormbreath Dragon and Inferno Titan. This list is also overflowing with resilient threats such as Huntmaster of the Fells and Pia and Kiran Nalaar, while still looking to play a value game with Tireless Tracker and Chandra, Torch of Defiance. Rather than play traditional (and very boring) interaction like Lightning Bolt or what have you, it's all about preventing opponents from ever casting spells in the first place.

This deck may look like a bit of a gimmick; the principal reason for this is that it is, in fact, a bit of a gimmick. It's a gimmick, however, that is incredibly well-positioned against one of the leading strategies in Modern. Big Mana decks – both Scapeshift and Tron – need a critical mass of lands to function, and the multitude of land destruction spells in this deck are out to stop that.

Mono-Blue Living End

A mono-blue list built around a black card? What a world we live in. For years, Living End has had its home in Jund shells, being cascaded out on the back of Violent Outburst and Demonic Dread. Amonkhet, however, brought us a new way to cheat out suspend spells: As Foretold not only allows you to snap off Living End the moment you play it, but also allows you to play Ancestral Vision without feeling bad about your life choices!

The real strength to this deck – something that traditional Living End lacked – is the fact that it can hustle so hard with countermagic and card draw. Living End is obviously excellent against creature decks, but this mono-blue version doesn't have to give up percentage points against decks like Storm and Scapeshift given its critical mass of counters. Casting a Living End with Cryptic Command backup is what's known in the business as "large game," and on top of that, the creatures are a little less embarrassing than some of the traditional Living End targets – no one is killing a Striped Riverwinder in Modern.

Corbin Hosler put this deck through its paces - if you haven't got across these videos, do yourself a favor and check them out!

Simic Merfolk

Speaking of Chosler – known to his friends as "Corbinhelm Commander" (at his insistence, I might add) – Bilbao may end up being the tournament at which Merfolk finally make a splash and get back onto the competitive scene. The splash this deck makes may end up being Magikarp-like in that it does nothing, but with the new additions from Rivals of Ixalan, it's now or never for the fish.

If there is a viable Merfolk deck, it will have been found for this weekend. There are too many great minds asking too many questions about the format for it to be missed – not to mention the recency bias many players will have as a result of the grand entrance of cards like Merfolk Mistbinder and Kumena, Tyrant of Orazca. The lists we've seen in the past weeks have been rough and unpolished – streamlined, consistent builds have always been the best way for Merfolk pilot to win, and I don't believe that's changed. Now, with 12 lords, a one-mana 2/2, and a three-drop with a Tolstoy novel's worth of rules text, Merfolk is poised to flood the tournament and send its foes to the briny deep.

And – of course – there are videos of Corbin playing his take on the archetype, for your viewing pleasure.

Next week we'll be in a position to sift through the data from Bilbao and see how the dust has settled on the Modern format. One thing is for sure: the Wild West landscape of the format is set to change, and I'm champing at the bit to see what comes of it!