friarsol wrote:That's how layers work:
7/18/2014: If
Urborg loses its abilities (for example, if it becomes a creature and then
Turn to Frog targets it), all lands on the battlefield, including
Urborg, will still be Swamps, but
Urborg won’t have the ability “Each land is a
Swamp in addition to its other land types.”
Urborg also won’t be able to tap to produce

, but other lands (including those that enter the battlefield later in the turn) will. The way continuous effects work,
Urborg’s type-changing ability is applied before the effect that removes both the type-changing ability and its own mana ability.
I googled a little more about that, this should make it very clear:
http://magic.wizards.com/en/articles/ar ... 2009-11-05I also read that whole article and the relevant part of the official rules, and i think i have a better understanding how layers work now.
The example you are quoting is different: If
Urborg "loses its abilities", that happens in Layer 6. The type-changing ability of
Urborg happens in Layer 4. That's why other lands would still be swamps.
However, with
Blood Moon and
Urborg and
Song of the Dryads, everything happens in Layer 4, so this will be decided with dependency.
(I understand that's probably not a simple fix, but i still wanted to make clear it's not working as it should right now, so it can hopefully be fixed at some point.)