bizarre ce texte gatherer....
Citation :
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 [type, supertype, or subtype]." 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 lands are 1/1 creatures that are still lands." The affected lands now have two card types: creature and land. If there were any lands that were also artifacts before the ability's effect applied to them, those lands would become "artifact land creatures," not just "creatures," or "land creatures." The effect allows them to retain both the card type "artifact" and the card type "land." In addition, each land affected by the ability retains any land types and supertypes it had before the ability took effect.
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."
comme je ne pense pas qu'il y ait de différence entre le "is" et le "becomes" (à part grammatical), je