In a world where colors are selfish/proud, what better land than this one? It's actually a bit weak in that it enters tapped (and I didn't want it better than Shimmering Grotto), but this can make your two-color deck actually try to play cards like Paolo's Bodyguard. It's also cool than, unlike cards like Reflecting Pool, two of these don't leave you without colored mana.

Wow, a universal Graven Cairns. Awesome. ETBT is quite a drawback; is it enough? Possibly not, but clever design nonetheless. Designing nonbasic lands in the spaces around Shimmering Grotto and so on is quite hard.

Remember that having this and another land while trying to cast Qasali Pridemage sucks. Late game, though, entering the battlefield tapped is a bit harsh. This may be balanced, but I'm a bit sad that this can potentially frustrate you a lot if you fail to draw your third land.

...And if you're trying to cast a two-drop gold card?

Exactly. That's what makes it frustratingly balanced.