Aven Trailblazer | Magic: The Gathering
Formats Aven Trailblazer is Legal in
Official Oracle Text for Aven Trailblazer
Domain — Aven Trailblazer's toughness is equal to the number of basic land types among lands you control.
—Belator of Esper
Official Rulings for Aven Trailblazer
2/1/2009 : How many lands you control of a particular basic land type is irrelevant to a domain ability, as long as that number is greater than zero. As far as domain is concerned, ten Forests is the same as one Forest.
2/1/2009 : A number of nonbasic lands have basic land types. Domain abilities don't count the number of lands you control -- they count the number of basic land types among lands you control, even if that means checking the same land twice. For example, if you control a Tundra, an Overgrown Tomb, and a Madblind Mountain, you'll have a Plains, Island, Swamp, Mountain, and Forest among the lands you control. Your domain abilities will be maxed out.
2/1/2009 : Aven Trailblazer's second ability is a "characteristic-defining ability." It applies at all times in all zones.