Maybe forced ETB, but a conditional bonus? "Chant land"?

Eeeep. Lands that tap for two mana are a very scary space. Ones that also have basic land types to make them fetchable by Flooded Strand, Farseek and so on? Absolutely terrifying.

Now requiring an enchantment is a very interesting hoop to jump through, though. It does defuse a lot of the problems with two-mana lands, which is Legacy decks getting a blisteringly fast start. Unless they're using Spirit of the Labyrinth or Hopeful Eidolon, they won't get a boost from this during the earliest turns where it matters most.

I think this is still plenty exciting enough without the basic land types, though. Don't get me wrong, I absolutely love dual lands with basic land types, but it is a massive boost to their potential, and a land that can potentially tap for two mana really doesn't need a boost like that on top.