I’m going to use a 1-5 star rating system, with 5 stars being format staples. To save space, cards of similar power level are clustered by their respective ratings.
**Updated on September 5, 2016
Lotus Bloom is more of a combo card that is used in decks that build towards one or two big turns. Don’t play this if you can’t abuse it.
Everflowing Chalice, Lotus Petal, Astral Cornucopia
Everflowing Chalice is best suited for 1-2 color decks with medium-high mana curves and/or mana sinks. Lotus Petal is the quintessential “ritual rock.” It is a one-shot effect for decks that need fast starts and/or big turns early. Astral Cornucopia works well in decks that abuse charge counters (i.e., Vorel).
Chrome Mox, Mox Diamond, Mox Opal
Chrome Mox is good in decks that need to burst out of the gate fast. Certain combo decks and aggro decks will want this, but it is not ideal for some slower strategies. Mox Diamond fits best into medium-high land count decks that want a fast start. Bonus points if you recover the discarded land later in the game! Mox Opal is nuts in artifact-heavy decks like Sharuum the Hegemon, but stay away from it otherwise.
Mana Crypt would see far more play if not for the financial barrier. If you can afford to buy/trade for one, put it in your most competitive deck and don’t look back. This thing is like Sol Ring on crack.
Despite giving Mana Vault the same rating as Sol Ring, it is slightly less versatile, and probably only slots into about 80% of Commander decks.
Sol Ring is good in 99% of Commander decks, so play ’em if you got ’em. It is the only ritual rock with no downside.
Myr: Copper Myr, Gold Myr, Iron Myr, Leaden Myr, Silver Myr, Plague Myr,
The Myr are almost strictly worse than the Diamonds, since being creatures makes them more vulnerable to removal and collateral damage from board wipes. If your deck plays cards like Skullclamp or Jor Kadeen, the Prevailer, then the Myr are a solid option. Otherwise, I would avoid these.
Diamonds: Charcoal Diamond, Fire Diamond, Marble Diamond, Moss Diamond, Sky Diamond
Moss Diamond is the least playable since Green has much better ramp options, but it merits consideration if your deck has mass land destruction. The diamonds are very playable in mono-color decks, but few multi-color decks, since the Signets are better alternatives. I could see playing a Diamonds in 2 color decks that really need another 2cmc rock to help ramp, but they are mostly suited for mono-color.
Medallions: Emerald Medallion, Jet Medallion, Pearl Medallion, Ruby Medallion, Sapphire Medallion
The Commander 2014 reprint did a lot to lower the price on this old Tempest cycle. These are most powerful in decks that want to play multiple colored spells each turn.
Talismans: Talisman of Dominance, Talisman of Impulse, Talisman of Indulgence, Talisman of Progress, Talisman of Unity
These are a slightly worse version of Signets, but they are still arguably the second best 2cmc rock in 2+ color decks. The 1 damage downside is not particularly significant in a 40 life format.
Signets: Azorius Signet, Boros Signet, Dimir Signet, Golgari Signet, Gruul Signet, Izzet Signet, Orzhov Signet, Rakdos Signet, Selesnya Signet, Simic Signet
The non-green signets are welcome in most 2+ color decks, while the green signets are okay in 3+ color decks and have a spot in decks with mass land destruction (or if your meta has a lot of MLD). The fact that these cost only 2 mana and fix 2 colors makes them worthy of consideration in most multi-color decks.
Let’s see: A 2cmc rock that enters tapped and doesn’t even add mana unless your graveyard is filled? Pass.
Guardian Idol, Manakin, Millikin, Dream Chisel, Hedron Crawler
More creature rocks that fit into a small subset of decks that need both small creatures and acceleration in one package. Millikin is the most interesting of these, as it has graveyard synergy. Dream Chisel is obviously only useful in decks with a heavy morph theme.
Fellwar Stone, Sphere of the Suns, Pentad Prism, Prismatic Lens, Star Compass, Etherium Sculptor, Helm of Awakening
These are variations on fixers with different downsides. Sphere of the Suns, Felwar Stone, and Pentad Prism are most effective in multi-color decks that need more Signet effects. Prismatic Lens and Star Compass are playable in decks with a large amount of basic lands, with the Star Compass doing a good Diamond impression in single color decks. Etherium Sculptor is a redundant artifact cost reducer. It synergizes with 1cmc artifacts and combos with Sensei’s Divining Top + Future Sight. Helm of Awakening is slightly narrower. Because it helps everyone, it should primarily be played in combo decks.
Mind Stone, Coldsteel Heart
These are more consistent and versatile than the previous group. Coldsteel Heart gets the nod over cards like Star Compass and Felwar Stone because it does not depend on lands to have an effect. Mind Stone provides solid acceleration while replacing itself in the mid-late game. Both of these are most welcome in 1-2 color decks.
The more expensive, but less painful version of Mana Vault is a great way to get a 1-3 turn boost. Grim Monolith loses some of its power in 3+ color decks and decks with low curves, but it shines in 1-2 color midrange/control/ramp decks.
The “battle rocks” as I like to call them, find homes in decks that need both ramp and creatures, as well as decks with equipment and other creature boosting effects. Don’t forget that you can add mana with these rocks even after they are creatures. In a pinch, you could tap them for mana to animate themselves, then use them for sacrifice effects like Attrition or Altar of Dementia.
Cameos: Bloodstone Cameo, Drake-Skull Cameo, Seashell Cameo, Tigereye Cameo, Troll-Horn Cameo
These are strictly worse versions of Ravnica Cluestones, but if you are short on cards or just need Cluestone #2, then the Cameos are passable.
Cluestones: Azorius Cluestone, Boros Cluestone, Dimir Cluestone,
Golgari Cluestone, Gruul Cluestone, Izzet Cluestone, Orzhov Cluestone, Rakdos Cluestone, Selesyna Cluestone, Simic Cluestone
While unexciting, Cluestones provide color fixing, ramp, and replace themselves in the late game. They are most playable in decks with high average cmc or decks that want to cast multiple colored spells in a turn.
Banners: Abzan Banner, Jeskai Banner, Mardu Banner, Sultai Banner, Temur Banner
The Khans banners are useful in 3 color decks that want early ramp with the potential to cycle. Play these in decks that want a second Commander’s Sphere.
Keyrunes: Azorius Keyrune, Boros Keyrune, Dimir Keyrune,
Golgari Keyrune, Gruul Keyrune, Izzet Keyrune, Orzhov Keyrune, Rakdos Keyrune, Selesnya Keyrune, Simic Keyrune
The “Battle Cluestones” are slightly better versions of Cluestones, since they provide bodies with (mostly) relevant abiities. The Simic one is probably the weakest, and the Rakdos probably the strongest.
Monuments: Atarka Monument, Dromoka Monument, Kolaghan Monument, Ojutai Monument, Silumgar Monument
This Dragons of Tarkir cycle is surprisingly useful in decks with the Fate Reforged dragon legends. They provide another dragon to trigger the attack abilities, as well as ramping into the dragons themselves. The downside is that these rocks cost a whopping six mana to activate.
Ramos: Eye of Ramos, Heart of Ramos, Horn of Ramos, Skull of Ramos, Tooth of Ramos
While Horn of Ramos is borderline unplayable in its color, the rest of these could see marginal play in mono-color decks with a lot of non-basic lands and high color requirements.
Borderposts: Fieldmist Borderpost, Firewild Borderpost, Mistvein Borderpost, Veinfire Borderpost, Wildfire Borderpost
These are arguably worse than the Cameos, since they require colored mana to cast at 3cmc, and their 1cmc mode is like a pseudo-Rupture Spire. I could see using the borderposts as a budget option, or in certain landfall / MLD decks where bouncing a land is beneficial. Otherwise, pass.
Obelisks: Obelisk of Bant, Obelisk of Esper, Obelisk of Grixis, Obelisk of Jund, Obelisk of Naya
The Obelisks are strictly worse versions of Darksteel Ingot, and a bit more narrow than Manalith, since they only cover the shards and not the wedges. If you are playing Esper or Grixis and need a second 3cmc mana fixing rock, then give these a go.
Alloy Myr, Shrine of Boundless Growth, Palladium Myr, Opaline Unicorn, Long-Forgotten Gohei
Two more creature rocks and a card narrower than Hank Hill’s urethra. Palladium Myr is the best of the bunch, since it can be used as a second Worn Powerstone. I find it hilarious that WIzards printed a strictly worse Alloy Myr (Opaline Unicorn) in Theros. I can only see these getting played in corner case scenarios or as placeholders for better rocks. Long-Forgotten Gohei is only marginally useful in casual Arcane decks.
Manalith, Pristine Talisman, Spectral Searchlight, Vessel of Endless Rest, Cloud Key, Semblance Anvil, Urza’s Incubator, Cryptolith Fragment, Magnifying Glass, Seer’s Lantern
Manalith, the Searchlight, and the Vessel are three takes on the 3cmc fixer rock. While the other two provide more options, Manalith is a perfectly reasonable budget option. Pristine Talisman is strongest in decks that cannibalize their life total or use life gain to draw cards or get other effects. Cloud Key is best in decks comprised of primarily one or two types of cards. Semblance Anvil is like a Cloud Key on steroids, but it’s a bit of a glass cannon because it opens you up to a 2-for-1. Urza’s Incubator provides a huge boost to tribal decks. Cryptolith Fragment provides a useful “group slug” effect for decks like Mogis, God of Slaughter, but is otherwise less than ideal. Magnifying Glass is unassuming, but may find a home in decks that make use of tokens and sacrifice effects. Seer’s Lantern is a neat little rock with a psuedo-Crystal Ball effect in the late game. It’s certainly not powerful, but can be played in decks like Keranos, God of Storms or even Kozilek, Butcher of Truth.
Darksteel Ingot, Basalt Monolith, Worn Powerstone, Commander’s Sphere, Unstable Obelisk, Extraplanar Lens
Darksteel Ingot is the safest mana rock because its Indestructible nature saves it from board wipes. Basalt Monolith has often been part of infinite mana combos, but is still solid on its own. Worn Powerstone is just a generic two mana boost for non-green ramp decks. Commander’s Sphere is useful in multicolor decks that want mana early and a cantrip late. It’s unexciting, but it gets the job done. Unstable Obelisk provides utilitarian removal on a rock, at the cost of only producing colorless mana. This is best used in one or two color decks, especially if you can recur it from the graveyard. Extraplanar Lens is tricky, in that it acts as a cheap mana doubler, but opens you up to get 2-for-1’d and severely out-tempo’d. If you play this as a pseudo-ritual and use Snow Lands, then its downsides will be somewhat mitigated. It should go without saying that this should be played in mono-color decks 95% of the time.
Ashnod’s Altar, Phyrexian Altar
While not technically “mana rocks,” the altars provide mana at a price. Savvy deck builders will use that downside to their advantage, and create strong engines or infinite combos. These should obviously not be played in creature-light decks.
Chromatic Lantern, Coalition Relic
These are the kings of the 3cmc castle because they fit into the widest variety of decks. Chromatic Lantern turns all your lands into painless City of Brass while it is in play. It is most useful in 3+ color decks. Coalition Relic provides the quantity of Worn Powerstone and the quality of Manalith all in one package. It is playable in decks of any color combination and is a strong default choice if you are unsure what to use.
Gemstone Array, Ice Cauldron, Paradise Plume, Urza’s Filter
Another group of cards with few applications. Gemstone Array is an option in decks that have charge counter synergies. Ice Cauldron has a lot of rules associated with it, so I’ll just post the Gatherer link to save space: http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=2407 . Basically, it allows you to put in an initial mana investment in order to cast the creature on a later turn for a discount. Paradise Plume is a more expensive Pristine Talisman. Urza’s Filter is a wacky little card that has strong implications for casual multicolor-only decks.
Thran Dynamo, Hedron Archive
This is most useful in decks that want to generate a lot of colorless mana. You will often see 1-3 cmc rock into Thran Dynamo into a big turn. I would be hesitant to run this in a 3 color deck since it does not produce colored mana. Hedron Archive bridges the gap between Mind Stone and Dreamstone Hedron, and is arguably better than both, thanks to its place on the curve. This card is a strictly better version of Sisay’s Ring and Ur-Golem’s Eye, making those cards nearly obsolete outside of niche strategies like mono-brown.
Gauntlet of Might
This is obviously made for mono- or heavy red decks only. In those decks it is strictly better than Gauntlet of Power due to its cheaper mana cost. Unfortuntely, it was only printed in ABU, so the price tag is nearly $120.
This only helps decks with many (25+) artifacts. Don’t let the one star rating fool you; Blinkmoth Urn is very powerful in the right deck. Remember that its downside can be avoided if you have a way to tap it on opponents’ turns!
Meteorite, Stone Calendar
I might be overrating this card slightly, but its easy to underestimate what a simple Shock effect can have in EDH. Run Meteorite in multicolor decks that want to ramp heavily and need that extra piece of removal/utility. Stone Calendar is yet another cost reducer, but this time it costs a hefty five mana. Play this if you want more redundancy for your Cloud Keys and Etherium Sculptors type cards.
The goggles, they do something! This is a very powerful effect that only goes into heavily spell-based decks that want to copy mid-to-late game haymakers. Keep in mind it can only copy red spells!
Gauntlet of Power, Gilded Lotus
Gauntlet of Power is deceptive and heavily meta-dependent. You wouldn’t want to run this in a mono-blue deck if your opponents had lots of islands in their decks. There is also the danger that it gets blown up immediately after you cast it, resulting in negative tempo swing. However, if it sticks around for even one or two turns, it can be game breaking. Gilded Lotus, on the other hand, is the default big mana rock. Any non-green deck with big spells should consider this card.
Workhorse, Mana Matrix, Planar Gate
Grenzo, Dungeon Warden is a popular destination for Workhorse, and it may have uses in other decks that manipulate and multiply counters. Mana Matrix helps instant/sorcery (Melek, Mizzix) decks, but at a whopping six mana, I would argue that it is seldom worth the card slot. Planar Gate is in the same vein, a six mana artifact that doesn’t immediately impact the board is often underwhelming and replaceable.
Literally a triple Mind Stone. Dreamstone Hedron is playable in non-green big mana decks.
I personally like Caged Sun more than Gauntlet of Power since it affects all lands you control, instead of just basics. It also does not help opponents at all. However, the steep 6 cmc makes this relatively slow. Try it out in 1-2 color decks that benefit from a huge surge of mana.
Altar of Shadows
Altar of Shadows is unlike any other mana rock, since it is primarily used for its ability to destroy creatures. If you have ways to both ramp into and protect the Altar, then it does a decent job in slow metagames. Stay far away from this card if your local meta is fast.
Now that’s what I call a battle rock! Mad style points to anybody who makes this clunker work.
Phew! Well that does it for my Commander mana rock guide. I hope that people can use this as a reference, without having to slog through search engines. I purposely left out some of the really narrow cards like Astrolabe and Black Mana Battery, since there are strictly better cards that do similar things, yet still seldom see play. Feel free to comment on synergies and anything I might have missed!