While Mana Crypt was featured in Vintage Masters in 2015, that was a Magic Online only set, which did no good for players of paper Magic. Before, there was only an extremely rare book promo and a DCI Judge Promo Foil. A single copy would set you back as much as $150 to $200. For most players, that's very prohibitive. While printing this at Mythic rare will still make it rather scarce, it will put a lot more copies out there.
So what's so great about Mana Crypt? In many ways, it's very similar to Mana Vault, a very popular artifact in Commander. The Vault doesn't untap on its own, and deals one domage to u for each upkeep that it remains tapped. It costs 4 mana to untap it on its own. However, the Vault provides you with 3 colorless mana, and there are plenty of ways to help it untap in both Legacy and Vintage.
The Crypt only gives you 2 mana, but it untaps every turn like most artifacts do. However, the drawback is that you have to flip a coin at the beginning of each upkeep.. If you call the flip wrong, you take 3 damage. Since there's a 50-50 chance of being right, it's usually worth the risk. It also costs nothing at all to cast, which is the card's greatest advantage. Having two mana before even dropping a land on the first turn is very powerful. That's why this card is restricted to a single copy in Vintage decks and is banned in Legacy. It gives you access to a lot of mana very quickly.
While I highly doubt that Mana Crypt will ever become the $4-5 card that it is due to two printings on Magic Online, it's going to become so much more affordable for those who want it. Yes, it will remain fairly expensive, and eventually, the price will probably creep its way back into triple digits. Most notably is that the Eternal Masters version has the same artwork as the highly sought after Judge Foil version. Plus, Eternal Masters comes with a foil in every pack, so the chances of opening a Foil Mana Crypt are much higher than normal.
How do you feel about this reprint? Is this a card that you've waited for to become more widely available? It's awesome in Commander and it will probably be Commander players who will want copies the month.