Tezzeret, Agent of Bolas has the ability: -1: Target artifact becomes and artifact creature with base power and toughness 5/5. Inkmoth Nexus is a non-artifact land that has an ability that makes it an artifact. Note that Tezzeret's ability does not say “in addition to it's other types”. So when Tezzeret makes Inkmoth Nexus into a 5/5, why is Inkmoth Nexus still a land (this is in the Gatherer notes, that Inkmoth Nexus doesn't stop being a land when Tezzeret's ability is used on it)?

Hi,

The Nexus is still a land because of this rule:

205.1b Some effects change an object’s card type, supertype, or subtype but specify that the object retains a prior card type, supertype, or subtype. In such cases, all the object’s prior card types, supertypes, and subtypes are retained. This rule applies to effects that use the phrase “in addition to its types” or that state that something is “still a .” Some effects state that an object becomes an “artifact creature”; these effects also allow the object to retain all of its prior card types and subtypes.

Example: An ability reads, “All artifacts are 1/1 artifact creatures.” If a permanent is both an artifact and an enchantment, it will become an “artifact enchantment creature.”

Since Tezzeret's ability says it becomes an artifact creature, because of 205.1b, it will retain all of its previous types, so the Nexus would be an artifact creature land.

Thanks,
Nathan Long
Magic Rules NetRep