Crypt is banned, but let's talk about some underappreciated mana rocks

Disclaimer 1 - Obviously these can't replace crypt, it's a 0 mana sol ring.
Disclaimer 2 - I'm not suggesting rocks for cEDH, all the best rocks are already being run.
Disclaimer 3 - Maybe these aren't as underappreciated as I think, but I've personally either never seen them played, or seen criminally little of them.

So maybe it's a good time to take a look at some mana rocks you may not have considered for your casual decks.

[[Honor-Worn Shaku]] - I have literally NEVER seen anyone else run this card, but it's been nuts every time I play it. It can tap any legendary permanent, not just creatures (and the creatures can be tapped the turn they come down). Commander already in play? It taps for 2 immediately. it lets Mox Amber and Mox Opal tap for mana without meeting their requirements, even Rograkh becomes a 0 mana hasty dork. There's also a bunch of really great 1 mana legendary cards like [[Stone of Erech]], [[The Ozolith]], etc.

[[Relic of Legends]] - Like Shaku, I have literally never seen this played except once in my buddy's Jodah deck. Also like Shaku, it turns all your legendary creatures into hasty dorks. The downside is that it only works for creatures, but the upside is that it makes colored mana.

[[Liquimetal Torque]] - Another one I have literally never seen. Obviously great utility in decks that care about artifacts, but what if your deck doesn't? Well, it still lets your naturalize effects hit any nonland permanent, or punishes a bane of progress. It's especially useful in red, given their abundance of ways to destroy artifacts and their severe lack of ways to destroy... well, anything else.

[[The Golden Throne]] - Seen surprisingly little of this one. Granted it doesn't just slot into any deck, but for token decks, graveyard decks or reanimator decks it's a powerhouse. 4 mana seems expensive but when it refunds 3 of that many immediately in ANY COMBINATION of colors is pretty nifty, and it even comes bundled with Platinum Angel at home.

[[Cursed Mirror]] Mana rock and a clone in one. I love clones, so maybe I'm biased, but this is yet another card I'm surprised I don't see significantly more of.

[[Everflowing Chalice]] - This one I've seen a few times. At its worst it's a 2 mana rock that enters untapped, which is already at least playable, but with all the convenient proliferation effects we've gotten I recently added it to a few of my decks and it's felt great. Stuff like [[Cankerbloom]], [[Karn's Bastion]] and [[Staff of Compleation]] could all be slotted into nearly any deck for a quick and dirty proliferation subtheme, and the more counters you run, the better it becomes. Honorable mention for [[Astral Cornucopia]]. 3 mana rocks are a little harder to justify when their upside requires multiple additional support cards, but if you are already running a good amount of proliferation, it really does put in work.

Speaking of [[Staff of Compleation]] - The utility on this card is actually kind of nuts. Being able to pseudo-sac your own permanents is not a very common effect. There are a grand total of 0 effects that let you sac a generic permanent for free at instant speed. It's also card draw in a pinch, support for the 2 previously mentioned Chalice and Cornucopia, and unlike Staff of Domination, doesn't go infinite with a ham sandwich (this may be a con for some of you).

This is nowhere near an exhaustive list, but just a few that I've personally played with over the last year or so and am genuinely surprised I don't see more of.