...what the..?

Is this a Land with Loyalty abilities?

Yeah. See "mechanical themes" page for an explanation, although I see while I wasn't paying attention Alex has made a host of new improvements including explicit links for individual mechanics.

I started designing the set with a random collection of woodland creature cards, and was looking for other ideas to add. I didn't want at that point to introduce a specific new mechanic that would require a greater knowledge of the set to appreciate individual cards, and somehow I came up with this idea.

It seemed really obvious: the loyalty ability can be used in a variety of interesting ways, but never will be so long as it has to be on scary mythic cards. Originally it was on a variety of card types, but lands seemed by far the most natural. My (one quick) playtest showed it reasonably interesting and not too fiddly, although unsurprisingly some were way overpowered :)

It's a really interesting mechanic. Even those like Arcane Scriptorium that can add mana without losing loyalty aren't "strictly better" than basic lands, because (a) they can be attacked, and (b) loyalty abilities can only be activated on your turn at sorcery speed.

Thank you :)