From "Worldly Counsel"
Domain - Look at the top X cards of your library, where X is the number of basic land types among lands you control.
From "Might of Alara"
Domain - Target creature gets +1/+1 until end of turn for each basic land type among lands you control.
I'm guessing this keyword mechanic was based from the Domain theme deck way back in the Planeshift expansion set, wherein you use land fetching cards to complete the five basic lands and play cards that abilities are based on the number of basic land types among the lands that you control.
I think this would be very interesting and fun for the current non-basic land infested Standard metagame. It also makes me think that 11th ed will be reprinting the Ravnica shock lands. We'll see about that next year but for now, we will be going back to basics in Conflux guys. Wooot!