Stormtide Leviathan | Magic: The Gathering
Formats Stormtide Leviathan is Legal in
Official Oracle Text for Stormtide Leviathan
All lands are Islands in addition to their other types.
Creatures without flying or islandwalk can't attack.
Official Rulings for Stormtide Leviathan
8/15/2010 : Stormtide Leviathan's second ability causes each land on the battlefield to have the land type Island. Each land thus has the ability to tap to add to its controller's mana pool. This effect doesn't change anything else about those lands, including their names, other subtypes, other abilities, or whether they're legendary, basic, or snow.
8/15/2010 : If Stormtide Leviathan loses its abilities, all lands on the battlefield (including those that enter the battlefield later on) will still be Islands in addition to their other types and will still be able to tap to produce . The way continuous effects work, Stormtide Leviathan's type-changing ability is applied before the effect that removes that ability is applied.
8/15/2010 : Stormtide Leviathan's third ability affects all creatures with neither flying nor islandwalk, regardless of who controls them. They can't attack any player or planeswalker.