The interior of Tazeem used to be home to Oran-Rief, a vast reef-rock forest.
Imagine a coral reef, brittle and spiny, but made out of rocks that twist hundreds of feet into the air. The reef might not have been alive, but it looked alive. Massive, sprawling root structures wrapped around brittle sandstone arches. Heavy brambles and thick undergrowth overwhelmed the rock, making it hard to tell what was branch and what was stone. Things grew fast, supernaturally fast, especially in the hollows and pit-caves where the midday sun rarely shone. Oran-Rief's explosive growth could take your breath away—figuratively and literally.
Oran-Rief was a wet place. The stone was porous, and water constantly poured from the high plateaus in sun-catching, heart-stopping waterfalls. The Giant Mantises and Grazing Gladeharts of Oran-Rief rarely went thirsty. Storms were common and spread quickly. The Roil was very active in Oran-Rief, and airborne creatures were at a disadvantage. Oran-Rief's Humans—the invokers, the survivalists—were always conscious of the forest's dangerous population of Hydras and Baloths. There was very little civilization inside the Vastwood, because it was too wild for anyone to tame. It was not a place you entered if you wanted to escape from the natural world. You were more likely to become a part of it.
Oran-Rief is dead now. The trees are gone. The creatures are gone. The rocks are brittle and chalky. The Eldrazi sucked the land dry. It is forfeit.
If Ruins of Oran-Rief seems familiar, it's probably because you remember a similar card from Zendikar:
Chilling, isn't it? While Jason Felix's Ruins of Oran-Rief doesn't show the exact branch that Mike Bierek depicted in the original Oran-Rief, the Vastwood, it's clearly meant to evoke a similar tableau. Both cards have a large tree dwarfing the left side of the frame, a large arch in the background, and another arm of the reef shadowing the top right of the frame. Both have a small group of "adventurers" climbing deeper into the frame—a group of either humans or elves in Oran-Rief, the Vastwood, and a column of Eldrazi Scions in Ruins of Oran-Rief.
The two cards are mechanically similar as well. Oran-Rief, the Vastwood taps to put a +1/+1 counter on all green creatures that entered that battlefield this turn. Ruins of Oran-Rief taps to put a +1/+1 counter on target colorless creature that entered the battlefield this turn. Oran-Rief might be a source of power for the Eldrazi now, but there are consequences for draining the land. Oran-Rief is not as powerful as it was when it was brimming with green mana. Nothing the Eldrazi do can change that.
Of course, the most interesting part of this card is the new "represents colorless mana" symbol. In past Magic expansions, this would have been a little "1" with a circle around it. Not so on Zendikar. That little box with the concave sides represents what the Eldrazi are doing to the land, and it does so elegantly.
In the history of Magic, "colorlessness" has usually been reserved for artifacts: objects that can be accessed by Planeswalkers regardless of their color alignment. It doesn't matter if you're a white mage or a blue-red one—you can cast Bonded Construct or Veteran's Sidearm regardless of which lands you play. There are a few colorless, non-artifact spells in the game—Karn Liberated is one, and Ugin, the Spirit Dragon is another—but they are exceptionally rare and they usually have a strong flavor justification for transcending color identity.
Ruins of Oran-Rief | Art by Jason Felix
The Eldrazi are different. Their colorlessness isn't one of transcendence, like Ugin, nor is it one of universality, like an artifact. The Eldrazi are colorless because what they do doesn't correspond to color identity as we know it. They eat color and what's left is...something else. Something that isn't colorless in the way that Mishra's Factory is colorless, but is clearly absent white, blue, black, red, or green mana. Call it the absence of color. The anti-color. The color out of space. Colorless in the strictest sense.
It is the closest thing to a sixth color of mana we may ever see.
There are Eldrazi-related cards in Oath of the Gatewatch that specifically require colorless mana to cast. You won't be able to play these spells without having a land like Ruins of Oran-Rief that taps specifically for colorless mana. This makes a delightful amount of flavor sense—now that the Eldrazi have sucked large swaths of Zendikar dry, they're able to use that energy to increase their presence on the dying plane. They drink, Zendikar dies, and they get stronger.
If you're building an Eldrazi deck after Oath of the Gatewatch is released, you'll have to think much more carefully about how many non-colorless lands you want to run. It will be possible to make a deck that only showcases the blighted, ruined parts of Zendikar—the parts devoid of color. It will be terrifying and alien to play with, as if the old rules of Magic don't apply anymore—like the whole idea of color and colorlessness has been turned on its head by something that doesn't belong.
I can't wait.