MTG Salvation

As I see it, the baseline for mana rocks is the following:

Mana Cost 2 - Generates 1 colorless
Mana Cost 3 - Generates one of any color
Mana Cost 4 - Generates 2 Colorless

To be cube-worthy, a card at that mana cost basically needs to do that, plus a little extra.

This one seems close. It's probably on par with something like Coldsteel Heart.

Kind of surprised it hasn't been mentioned yet. What do you all think?

Skipping from 2 to 4 mana is way more crucial than skipping from 4 to 7

This needed to enter untapped for me to consider it. 4cc+ for mana rocks are just too expensive, and I only consider the ones that enter untapped because they can function as cheaper the turn you play them.

As far as mana rocks go, this is good but not great. ETB tapped is a big drawback. I think this is a narrow miss for my cube, and my cube is already huge. There aren't a ton of four mana cards to compare it too, Khalni Gem being the most interesting for its fringe land synergy. I might play it over Hedron Archive if I played that, since lots of decks need color fixing more than the cards. I think Coldsteel Heart is pretty good, but more decks have time for a two-mana rock than a four-mana rock. The "two different colors" bit mostly just means that it can't be UU for Counterspell (or bluffed counterspell) by itself.

Of note, as with anything that taps for multiple mana, this is great with untappers like Kiora, Behemoth Beckoner, but most of those don't hit artifacts.

I think it’s extremely fine.

If I ran a cube that was big enough to run Thran Dynamo and Hedron Archive and Everflowing Chalice, and still want more 4-mana mana rocks, I’d consider this along with Sisay’s Ring and the Converge Chronomaton dude. But tapping on ETB factors pretty big in my Dynamo/Gilded Lotus play patterns

Every 3cc mana rock in my cube taps for 2+ mana. I think this is well below the curve for what I'd expect from a cubeworthy 4cc mana rock (which should either tap for 3 mana or generate card advantage). It needed to either enter untapped, tap for 3 mana, or have another upside on it, IMO.