So, I have a bit of a designer handicap where I love multicolored cards, narrow build arounds, and great art. With that said, I come to answer one of M21's greatest questions: Am I really this stupid?
Let's take a look at the shrines by color to see if they cooperate with each other and if they can support any themes. Let's also consider how many shrines you need in play to make the cards look good in a low-mid power environment and how we feel about the baseline effect with one shrine.
So, the synergy here is basically nothing. They both slow the game down but it's not terribly efficient.
The Sanctum is very "retail draft removal" level and is the least appealing of all 10 of these to me. It gets good, but not until 4-5 total shrines in play. Otherwise, it's basically shit. The only application I see for this one is to increase your density of Shrines. The only theme it's playing with is enchantment decks, and that's a stretch. It's a cheap way to build shrine count, and the dedicated shrine deck is likely the only one that wants it.
The Honden, however, looks alright. The life can really add up with even just one shrine and starts looks pretty good at 2-3 shrines. This could take out some aggro matchups for you. Obviously, this thing is great in a life based deck, which often wants both frequent triggers and lots of total life. Likely a BW deck. As you'll see, the B Sanctum plays along well.
Loving how both of these are such classic blue cards. Draw more. Excellent. Every blue deck could use them, but are they any good?
To me,
Phyrexian Arena is a great example of an ongoing draw engine that's strong in a slower environment. To get similar results to Arena, I'd argue both of these need two shrines in play. That's very reasonable and I think they're both decent cards. The big downside to these is that you'll likely deck out if you actually go all-in on shrines, but that can be worked around.
These two don't play along well at all, but I think that's okay because they're both so thematically black.
The Sanctum here is great. For just two mana, you're getting a repetitive life gain trigger. With a second shrine in play, it's like a lifelink bear. The fact that it functions on its own is valuable and it comes down quickly for shrine count.
The Honden is tricky because its usefulness is tied to the number of cards in the opponents hand when it hits play. It will often shut down interaction during your turn from the opponent, seeing as it will come down late. With two total shrines out, this adds inevitability to a lot of matchups. Not too bad.
As has been the case, you're really going to want a second shrine in play for these. Once you have it, these will really chip away at the opponent's board. I'm digging the potential of both of these. If you get both out at once, you'll be able to shoot down a lot of threats.
These both do a great job supporting green themes, so that's a strong start.
For ramp, you can find better rates than the Sanctum, but it's totally passable with no other shrines in play and decks may even run it with no chance of hitting a second shrine, depending what your format's ramp looks like.
The Honden is looking pretty bad as a solo shrine. As a sorcery, we'd expect to get four tokens immediately for 5 mana. You're going to want three total shrines (or two and a slow game) to make this thing get beyond that theoretical sorcery. That said, once it surpasses that sorcery, you'll continue getting dudes until this thing is answered or your opponent is overwhelmed.
I also dig the token art.
Conclusion(sort of)
None of these shrines are great on their own, but once you hit 2-3 in play, they all start looking pretty good. If your environment is slow enough, you could totally support them. That said, you're likely gonna need to run doubles in the draft if you want to get a decent density of shrines. Unlike a tribal deck that encourages pure collection, this feels more like a side strategy to add an occasional twist to your draft.
From there. I'd certainly encourage some sort of enchantments theme in the format since you already have a decent quantity. Lifegain is supported by two of the shrines, so you might as well give that a whirl in your theoretical low power environment. Especially with the new BW tools from M21. The blue and red shrines slot in anywhere. The green ones will also work in many decks. That's eight of the ten slotting in pretty easily, so I like the potential.
Another option is to just throw in two sets of the 11 cards on top of your existing environment for a while to try them out. I don't anticipate these will hold much value, so why not?
Beyond the obvious enchantress-type synergies,
Paradox Haze plays with the Hondens (but not the Sanctums).
Sphere of Safety does a decent shrine impression. Brad's BRILLIANT GW Legends theme can help with
Captain Sisay grabbing shrines (discussion starts here:
https://riptidelab.com/forum/threads/the-selesnya-conclave-gw.1848/#post-81448).
Clever Impersonator can copy an opponent's shrine that you lack. Any other less obvious interactions you guys have?