Reprint from early core sets. This was originally uncommon, but the effect has moved to common despite the rules complexity: Contaminated Ground. Here's a little reminder from gatherer concerning that complexity: "The enchanted land loses its existing land types and any abilities printed on it. It now has the land type Swamp and has the ability to tap to add to its controller's mana pool. Evil Presence doesn't change the enchanted land's name or whether it's legendary, basic, or snow." That last line isn't all that intuitive. Also it's odd that there's no mention of non-basic lands. Can I Wasteland an Evil Presenced Library of Alexandria? I'm assuming I can't.

The rules on this are fairly well established, and the effect has been common for many years: see Dream Thrush and Phantasmal Terrain in Invasion, and Sea's Claim and Spreading Seas more recently. So common is the right place for this.

There are certainly rules subtleties to the effect, but it's at least well-established. (And yes, you can. The ruling you quoted said "Evil Presence doesn't change... whether it's... basic"; so a Library of Alexandria under Evil Presence is still nonbasic, so it can be hit by Wasteland.)

Oh I see. I suppose I would have written it "Evil Presence doesn't change the enchanted land's name or whether it's legendary, basic or non-basic, or snow." But then, this line is only interested in asserting that evil presence doesn't affect supertypes, right?

Well, it's saying that it doesn't affect them either way. "Doesn't change whether it's basic" means the same thing as "Doesn't change whether or not it's basic".

I see (maybe). I suppose I had assumed that basic and non-basic are two logically separable supertypes that may be treated in isolation of one another, rather than a pair of contradictories, the one describing that which is mutually exclusive from the other. The clue that they have this logical relationship is the use of the prefix 'non', which implies that basic/non-basic forms a dichotomy such that anything that is not basic is nonbasic and vice versa (I feel a little silly for having missed this).

But I'm still confused. If non-basic-ness is defined by way of its being the contradictory of basic-ness, then it is implied that wherever we have a basic land, we cannot at the same time have a non-basic land. So, because swamps are basic, my evil presenced library of alexandria is basic. But if it can still be wastelanded, it must still be non-basic. How can it be both without breaking the rule of non-contradiction?

I suspect that my mistake is bringing first-year logic to bear on a set of rules that is quite a bit more sophisticated than I realize.

Oh yeah, it looks like evil presence found its way into New Phyrexia. I was a little disappointed that the only swampwalk I could find in the set was on the Black mythic rare. Actually, I'm not sure why it got reprinted in that set at all, especially since the spread of phyrexia isn't exclusively Black anymore.

Ah, the mistake you were making is in thinking that swamps are basic. From the original Badlands cycle through Godless Shrine to the modern Leechridden Swamp and Urborg, Tomb of Yawgmoth, something being a swamp - having type Swamp - has never implied it's basic. The card with name Swamp has supertype Basic, but there's nothing in the rules to imply that something that has or gains the type Swamp is basic. A subtle point, I'll agree!

Cool, now I get it. No wonder I was limited to just 4 badlands to a deck. Thanks for your help.