You can activate that ability multiple times per turn and grow this as big as you want

You can also just pump excess mana into it without turning it into a creature, so it doesn't eat removal. Nice.

I'm predicting we'll see this one in some standard decks.

With a solid colorless manland and a bunch of mono-color utility lands*, this set could do a lot to encourage mana bases with fewer colors.

*Okay, the DFC's aren't "utility lands" in the traditional sense, but the impact is the same.

Hello new (quasi)infinite mana sink. I look forward to playing you with Braid of Fire

This is going to do some serious work in eldrazi tron.