You will find it can be very difficult to stick the combo pieces for two full turns to allow going off. Many decks in the format are packing Enchantment hate for Blood Moon currently, so watch out for tech out of the sideboard, and do not go too all in on the combo line-of-play.
Knight of the Reliquary + Retreat to Coralhelm
:
While this is not an infinite combo, the deck plays 9 Forest/Plains, allowing you to tutor for up to 9 extra lands when going off with Retreat to Coralhelm, pooling some amount of mana while doing so. You can use these lands to tutor for fetch lands, which you can then sacrifice to themselves to continue to fill the bin.
This combo may be finished off by grabbing a Kessig Wolf Run to provide trample to your Knight of the Reliquary for lethal.
Azusa, Lost but Seeking + Ghost Quarter + Ramunap Excavator
(or fetch lands):
This synergy allows you to play up to 3 Ghost Quarters per turn, or crack 3 fetch lands per turn when trying to build your land base. The combo can be utilized without Azusa effectively as well, allowing this same repetitive behaviour, but only once per turn.
Courser of Kruphix + Ghost Quarter
:
This is a more awkward synergy, but can be a very useful tool against aggro, such as Burn when trying to squeeze out life. Playing a Ghost Quarter and sacrificing it to destroy one of your own lands can net you mana as if you had still played another land (tap the target land before sacrificing), as well as allowing for multiple Courser triggers per turn.
This becomes exaggerated with more Courser of Kruphix on the field, as well as with Ramunap Excavator and Azusa, Lost but Seeking in play.
Below, we'll go through the card choices for the deck, and explanations of why they did/did not make the cut.
Courser of Kruphix (4)
Courser of Kruphix is the core value engine of the deck, and what a good portion of the deck is built around. Providing pseudo-topdeck control, gaining life, and providing a big body to block, or fearlessly attack with early game Exalted triggers.
This card is one of the main reasons to play the deck in my opinion, and is why I have chosen to go a land-interaction heavy route. A single Courser of Kruphix almost negates fetch+shock detriment, and >1 Coursers actually allow you to gain life off the fetch+shock interaction.
Other interesting interactions also present themselves through Courser of Kruphix, such as utilizing Ghost Quarter on your own lands for incremental lifegain against aggro decks. It's the small things like this that make this deck so interesting and enjoyable to play.
Ramunap Excavator (1-3)
This card allows some of the more broken interactions in the deck to run. Ramunap Excavator is fantastic in a lands-matter archetype, as all of your high-value lands which require sacrificing themselves can be recurred each turn as long as your Ramunap Excavator stays on the battlefield.
Ghost Quarter and fetch lands are two of the best targets for utilizing land recursion out of the graveyard, with Horizon Canopy also providing a strong draw engine in the late game. If you are able to play Azusa, Lost but Seeking while you have a Ramunap Excavator on the field, these interactions become that much stronger, as you are now sacrificing Ghost Quarter 3 times per turn, heavily punishing greedy 3+ color decks.
Azusa, Lost but Seeking (1-2)
Azusa is a niche card in the deck, but an absolute powerhouse when she goes online. Allowing many of our strong land interactions to be multiplies, Azusa, Lost but Seeking is worth including in some quantity. In my build here, I've chosen to run 4x maindeck Chord of Calling which in turn makes finding low-quantity cards very simple as the match goes on.
As mentioned above, Azusa, Lost but Seeking and Ramunap Excavator allow us to exploit things like multiple recurred Ghost Quarter per turn, as well as setting up early mana fixing via recurred fetch lands. While all of this value is being generated, you can also find lifegain from these interactions if 1 or more Courser of Kruphix are out on the battlefield.
In a list not playing Chord of Calling I'm not certain Azusa remains as prominent, so it may still be considered as it does meet the criteria of Collected Company.
Knight of the Reliquary (4)
Knight wears multiple hats in the deck, playing both as a part of the land engine, as well as a win-condition in partnership with Retreat to Coralhelm. This combo is often the focal point of Bant Company decks, though only resides as an alternate win-condition in this build.
The combo is fairly straightforward, though is not infinite and thus requires you to display the entirety of the combo. With a Knight of the Reliquary and Retreat to Coralhelm out on the field together, you may tap Knight to sacrifice a /, and search for a land to put onto the battlefield. When the land enters, Landfall is triggered on Retreat to Coralhelm, allowing Knight to untap and repeat this process. You then repeat these steps until the graveyard has enough lands to allow for a lethal attack with your Knight. If blockers will stand in the way of this attack, Kessig Wolf Run provides trample and +X/+0 to get over them.
Aside from the combo, Knight of the Reliquary plays into the above land engine very nicely, as it allows us to tutor for any utility lands in our deck that we need. The deck plays 9 /, thus allowing us to sacrifice up to 9 lands throughout the game. Common utility tutor targets will be Ghost Quarter, Kessig Wolf Run, and even things like Horizon Canopy if you run out of steam and need a draw engine.
