Domain is an ability word.
It appears in italics at the beginning of an ability that counts the number of basic land types among lands you control. (An ability word has no rules meaning.) Domain abilities first appeared in the Invasion block, although the word "domain" didn't appear on those older cards.
- Each domain ability has a different effect. Read each card carefully.
- To determine the number of basic land types among lands you control, look at the lands you have in play and ask yourself whether the subtypes Plains, Island, Swamp, Mountain, and Forest appear within that group. The number of times you say yes (topping out at five) tells you how powerful your domain abilities will be.
- 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.
- A number of nonbasic lands have basic land types. These include five Shadowmoor nonbasic lands, the Revised Edition "dual lands," and the Ravnica block "dual lands", among others. 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.
- A domain ability that appears on an instant, sorcery, or activated ability checks the number of basic land types among lands you control just once, as that part of its effect is applied. This value won't change even if which lands you control changes later in the turn.
- A domain ability that appears on a static ability continually checks the number of basic land types among lands you control. If that number changes, the effect of the static ability will change accordingly. For example, if you control a Swamp and two Forests when Matca Rioters comes into play, Matca Rioters will be 2/2. If you play an Island later, Matca Rioters will become 3/3.