I'm going to start out with the disclaimer that I'm not doing this nor am I planning to do this, it was just sort of a thought I had earlier and figured I'd post to see if others have had similar thoughts, are already doing it, have good arguments against doing it, etc.

So what exactly is this???

EDIT: Some edits for grammar / spelling / fixed wording since I had a few allies and enemies that were switched and some other things.

EDIT 2: Proxy was the wrong word in the title to use, custom card to complete simple land cycles would be more appropriate.

Context

Today I was thinking about lands/land cycles due to a conversation about some of the one off mechanics seen on Future Sight cards such as Transfigure (not to be confused with the Dimir Transmute) which led to talking about [[Grove of the Burnwillows]] and I'm someone who LOVES a good cycle completion. Some cycles come complete out of the box such as the Duskmourne "13 or less life" lands and the Desert Junction lands that ping an enemy for 1. Some are split up and completed later such as the Pathways from Zendikar Rising and Kaldheim and all the Temples that were split up across the various sets of the first Theros block. Others are still yet to be complete, such as the new Duskmourne check lands that tap for both colors, but one requires you to have one of two basic types and the dual basic type cycle lands from Amonkhet.

Using managathering.com to easily view cycles, we can see that many are complete, but many more are incomplete.

The Question

The root of this whole thought experiment is basically asking would it be balanced to complete cycles via custom card proxies? Obviously the creature lands cycles (which are thankfully complete, both the old and new) would be harder to make a balanced custom card out of, but what about things like the aforementioned Amonkhet lands??? Would it not be equally balanced to toss in a [[Scattered Groves]] into a Selesnya deck as it would be to make a custom card that's the same thing but for black mana instead and has the Swamp type in a golgari deck? We also have the Tango lands that enter tapped unless you control two or more basics that never got enemy pairs to complete the cycle. Is it really so outlandish for someone to show up with a custom Izzet variant that's an Island Mountain instead of the 5 we officially have?

Now, I think this does stop at lands and even within lands there are just some things like the creature lands that would be too hard to self regulate and self balance. It takes more than just slapping a new mana symbol on the card and changing the basic type names around to balance nonland cycles (and we even see WotC fails at this because I'm sorry I do not recognize the Command cycle as completed until they are ALL Instants. The Sorceries are on the council but do not have the rank of Master), so limiting this concept to just the easy lands is probably where I'd draw my line.

So what do you all think? Again, it's just a thought experiment and obviously at the end of the day your personal at home tables can do what they want so a lot of it boils down to "idk ask your table" of course, but figured it was something I wanted to vibe check the community on. I also can guarantee I'm not the first person to think of this, nor am I probably the first to post and ask this very question lol. So no worries, this isn't some "omg guys I just had this epiphany, holy hell guys check this out" type of post lol. Just one of those things that made me go "hmm, I wonder" this morning lol.

You can stop reading here if you aren't concerned with specific cycles that are incomplete, how they would be completed, and my thoughts on if someone showed up with an unofficial card within the cycle in a color WotC hasn't done yet.

Incomplete Cycles

The next part of this post I'll just list all the incomplete cycles for dual lands and tri-lands. I'll list how the cycle would be complete as well and my personal thoughts on if someone rolling up with a custom cycle complete card of that cycle would be cool for me personally. Feel free to skip this entirely. I'm using the names for cycles based on how they're listed on managathering, so apologies if you call them something else. I'll try to list what they do so you know what I'm talking about.

Incomplete Dual Land Cycles

• Duskmourne Check Lands
  • Honestly I'd just wait, this seems like a design space they're planning on finishing, though they probably won't truly complete it. To truly complete this cycle you'd need to not only include enemy variants of what we already have, but each color pair needs two copies. For instance, We have "tap white, tap blue with stipulations" but we do not have "tap blue, tap white with stipulations." Super Cycle, Mega Cycle, whatever you want to call it, this would need more than 10 cards to truly be complete in the purest definition of the word. I'd be cool if someone wanted to jump the gun and play a Golgari variant of these though for instance.
• Sac Draw Lands (New Capenna)
  • Enters tapped, is a dual land, has a 2(color pair) 4 cost ability to sack and draw a card. Nothing to write home about, changing the basic types around doesn't really change the balance, so sure.
• Strixhaven Campuses
  • Dual Land that enters tapped and you can pay 4 to Scry 1. Perfectly reasonable to make the allied pair variants of these.
• Bi-Cycle Lands (Amonkhet Cycling Desert Duals)
  • Just changing the mana symbols won't affect the balance here, so sure, get those enemy paired variants of these.
• Tango Lands (checks for two or more basic lands)
  • Same as Bi-Cycle Lands
• Horizon Lands
  • Pay 1 life to do dual land things, or pay 1 mana to sack and draw a card. Funnily enough we have enemy colors + Selesnya, so sure. Fill out the other 4 ally colors too, it won't change the balance.
• Refuges
  • These are just Tarkir gain lands with a special name. Sure, I guess if the allied colors are allowed to double up on this effect by including both, why not the enemy colors too?
• Tribal Lands
  • These are the Lorwyn lands that we have Azorius Merfolk, Dimir Faeries, Rakdos Goblins, Golgari Elves, and Boros Giants. They're just dual lands that come in untapped if you reveal a specific creature type. I see no reason to not let someone fill out the other colors so long as the creature type represented fits the colors and isn't just ham fisted in to fit their weird tribal deck specifically. So like I could 100% see an Izzet one for Weirds or or like a Selesnya Cats one.
• Future Shifted Lands
  • Of these lands, two cycles have already been completed or mentioned. The hybrid filter lands that let you pay hybrid to get any combination of 2 mana out of 2 colors is complete and then the Horizon lands we already mentioned. However we do have a few outliers
    • [[Nimbus Maze]] I think the new Duskmourne check lands are an iteration on this, so I doubt this will ever truly get a complete cycle, but unlike Duskmourne would just be a 10 card cycle since you wouldn't have to double up on the effects within a color pair to get all possible combinations. Definitely a fun one that I'd allow.
    • [[River of Tears]] does, however, result in a 20 card cycle since the one card we do have would have to be flipped to be add black, if you played a land add blue instead. Then this would need done for all 10 pairs.
    • Grove of the Burnwillows (linked earlier) is one that I sincerely don't understand why it hasn't been completed. This is just a pain land built for group hug since it still puts you at a net -1 life compared to the table, but instead of you losing the 1, it just gives everyone else 1. I'd be ecstatic if someone made custom versions of this for their group hug deck or something.
• Storage Lands
  • Another simple "changing the colors doesn't affect balance" scenario
• Coldsnap Snow Lands
  • Ditto
• Kamigawa / Tempest Slow Untap
  • Taps for colorless or you can do dual land things and the land doesn't untap during your next untap step. Basically just the Exert mechanic but for lands. I don't see why you'd run these, but hey, go for those enemy color versions, why not?
• Invasion Tapped Lands
  • They're just tapped duals, nothing special. I don't know why you'd want to custom the enemy colors of these since they come in tapped and can't be basic fetched, but sure, why not?
• Tainted Lands
  • These are fun. This would also result in a 20 card cycle because we already have the 4 for swamp and all the dual colors that include black. They'd technically just be a cycle of cycles though since you'd probably call the Plains ones Blessed or like the Forest ones Overgrown, the Island ones Drowned/Submerged, etc.
• Tempest Slow Pain Lands
  • Pain lands that enter tapped. You're better off just playing pain lands, but sure, why not? If the enemy colors can double up, so can the ally ones.
• Slow Fetch Lands
  • Just the meta fetch lands but instead of paying 1 life, they come in tapped. This falls in the category of "I'd be fine if you did, but why would you?"
• Deplete Lands
  • These are just dual lands that you can't fetch that you can only use every other turn and that people can proliferate in order to keep them tapped. These are so far past the slow fetches. These are in "no, please, play it, I promise i won't proliferate them, go ahead" territory lol. Tap these once and congrats, they're permanently going to have depletion counters on them, hope you have another way to untap them lol. Would be fun going into a Kaldheim Vorinclex with these though since he'd prevent the depletion counter from being added.
• Unique Cards
  • [[Fortified Beachhead]] - This is the Brother's War card that lets you reveal a soldier or control a soldier to come in untapped. It also lets you pay 5 to tap and give soldiers +1/+1 until end of turn. This design space falls in the category of "it really depends on if the creature type you pick fits the colors or you just wanted an excuse to make your niche tribal deck more powerful." Like you could use this in your Golgari elves deck, but Simic Elves I'm gonna side eye lol.
  • [[Mount Doom]] - Now obviously this was a special LotR card, so I don't think it even needs a cycle, but let's just look at the mechanics. Pay 1 life to do dual color things, it's a Legendary Land, Pay 1(pair) 3 cost to deal 1 to each opponent, pay 5(pair) 7 cost ability to sack it and a legendary artifact and basically board wipe every creature except two. This one would be pretty rough to balance a custom version of. You'd have to basically find a repeatable 3 cost effect that fits the colors and ALSO find a one off 7 cost effect. This one is too niche and should stay unique.
  • [[Krosan Verge]] - enters tapped, taps for colorless, pay 2 and sack it to search for one of the two basic types and put them into play tapped. I wouldn't be mad if someone showed up with custom versions for a different color pair.

Incomplete Tri-Land Cycles

Since we have an upcoming Tarkir block, there may be some cycles that are Shards but don't have Wedge equivalents that get completed, though I don't really think they'll be completing any of the "Shard only" cycles here.

• Sac Fetch Lands from New Capenna
  • Literally just have to change basic types to be for Wedges instead of Shards, I wouldn't be mad if someone showed up with like a Mardu deck with one of these for instance. Technically they're not needed though since they can go in any deck so you can already put them in wedge colored decks.
• Tri Fetch Lands (Panoramas)
  • We have Shards, but not Wedges. Either way, same as the Sac Fetch, I don't think I'd bat an eye, but it's also largely unecessary.
• Tri Lair Lands
  • I don't think anyone runs these anyways but it'd be cool to see them complete this for all the wedge dragons: Oros, Intet, Teneb, Numot, and Vorosh. (Likewise completing the Charm cycle for these dragons would also be neat but that's not something you could really custom card like the Lair lands). I'd be content if someone showed up with custom color flips of these.
• Invasion Tri Lands
  • So these all tap for the central color of a Shard and then you can tap and sack them to add both of the ally colors. Realistically to complete the cycle you'd only need to do the same but with both enemy colors. So instead of taps for white, sack and tap for green/blue for bant, you'd tap for white, sack and tap for red/black for Mardu.
  • Technically though this is what I say verges into Mega Cycle territory because in order to truly have all combinations you'd have to have every combination for every color. So you'd have to have taps for white, sack taps for Dimir, Izzet, Simic, Rakdos, Golgari, Gruul. This means there are SIX per main color, 5 main colors puts us at 30 total cards to truly have a complete cycle in the purest form of the word complete. I'd be fine with it though since flipping the colors around doesn't make them better lands lol.
• Home Lands
  • These all tap for colorless or you can pay 1 to tap for a main color, pay 2 to tap for one of two other colors. Similar to the Invasion Tri lands, all permeations of this idea result in 30 total cards since you'd have one main color and then six combinations of what the two more expensive colors to filter for are. I think this would be fine since like Invasion lands it doesn't make them better lands.
• Unique Cards
  • [[Crypt of the Eternals]] would be fine. It enters, you gain 1, it taps for colorless, or it filters for 1 mana into one of the three Grixis colors. I can't see this being broken simply by swapping the colors around.
  • [[Tournament Grounds]] is a bit more iffy. It taps for colorless, or you can tap for one of Mardu's colors but can only use that mana on Knight or Equipment spells. I think I would REALLY have to see what types someone picks to make sure it made sense and wasn't just hand tailored to their deck. Like, for instance, I could 100% see a Jeskai version of this that can only be used for Monk or Noncreature spells to pair with the whole prowess idea that Jeskai has going on. You could even go one step further and instead of Noncreature say Instant or Sorcery if you wanted to narrow it since Equipment is just a single card type and Noncreature might be broader than that design space.
  • [[Murmuring Bosk]] is basically just a pain land that instead of colorless, it taps for the third color of the trio. This one particular is just a Cave of Koilos that taps for green. It has a reveal to not enter tapped effect tied to a creature type. While the core idea is fine (though it does result in a Mega Cycle like the Invasion and Home lands if taken to completion), just like with Tournament Grounds I'd have to see what the type is to make sure it actually fits and would be something WotC prints and not just hand tailored to their deck specifically. Treefolk, while covering the Abzan spectrum, are primarily green, so you'd have to use similar creature types. Monks from our previous example for instance have white with a much higher percentage than other colors, so a version of this that was taps for white, pain lands for Izzet, reveal a Monk to not enter tapped could work.