First thing you should always do when brewing decks is figuring out what you can do with the mana. Of course, only a select few actually do this, because it’s much more fun to start with those interesting cards or synergies. Still, this is the way you should do it. (Yeah, I don’t either.)

Ixalan is a weird set. They’ve broken the usual symmetry of how colors work. There’s two two-colored factions (Vampires and Merfolk) as well as two three-colored ones (Pirates and Dinosaurs). How do they plan to make the mana work here, I don’t really know. We do have the checklands coming back, which do help with playing shards. So, since we know we want to play pirates, we should start with figuring out what lands we have for Grixis, assuming we want to play [scryfall]Admiral Beckett Brass[/scryfall] and since she’s a tribal lord, we definitely do.

We have the following duals:

Supposing we want to play a full set of each, that would give us 16 black sources, as well as 12 of each blue and red, with 20 lands. We could also use [scryfall]Aether Hub[/scryfall], but I’m not really interested in that. Instead, I want to play a little more lands than we actually need otherwise, because with this configuration, we’ll have eight cyclable lands. So, two Islands and two Mountains would give us a nice 14 sources for each red and blue. Maybe thrown in a couple more Swamps just because they work with each of the checklands. That would make it 18 black sources with 26 lands, which is admittedly quite a few.

So, what about the Pirates themselves? Let’s start with what we had already.

Do we want all of these? Not sure, but [scryfall]Skyship Plunderer[/scryfall] does have some nice synergy with [scryfall]Metallic Mimic[/scryfall]. I’m not sure we want to play a full set of Kari’s, because there’s plenty of two mana options in Ixalan. Also, it sort of feels like we still want a few more pirates either from this or the next set to make this all worthwhile…

Okay, so how do we choose from those?

I want to play [scryfall]Hostage Taker[/scryfall], because it’s a good pay-off for all the mana we play. I don’t think I want to play [scryfall]Captain Lannery Storm[/scryfall], because he doesn’t seem to do enough. I think. It’s hard to evaluate the treasures, although Legendary 2/2 haste for three mana seems like something we can live without.

So, how about this:

[deck]
[creatures]
4 Metallic Mimic
4 Skyship Plunderer
2 Kari Zev, Skyship Raider
4 Kitesail Freebooter
3 Fathom Fleet Captain
4 Ruin Raider
4 Deadeye Tormentor
2 Admiral Beckett Brass
4 Hostage Taker
3 Direfleet Captain
[/creatures]
[lands]
4 Spirebluff Canal
4 Fetid Pools
4 Canyon Slough
4 Dragonskull Summit
4 Drowned Catacombs
2 Island
2 Mountain
2 Swamp
[/lands]
[/deck]

That gives us 20 two-drops, eight three-drops and six four-drops and no spells. This would rely on our pirates to work as answers to certain cards. The curve is pretty low for 26 lands. Maybe we should cut down on the blue somewhat, so we can play fewer sources for it, but I wouldn’t want to play less than 14 anyhow.

Well, there’s a lot of options, but it’s hard to say which ones will be any good. I guess we’ll see. There’s also chance that with quite a few sweepers in the format, Pirates might be totally useless as they require quite a bit of synergy to work.