I was playing a game last night with a guy who was playing a new Simic Gatecrash deck, and he claimed that if he made a land into a creature, it counted as entering the battlefield, thus triggering evolve (or other "enters the battlefield" abilities).
I thought this was incorrect, being that the creature didn't actually enter the battlefield, it was just created.
Which of us was right?
"Enters the battlefield" means moving from a zone besides the battlefield into the battlefield. As you say, it didn't actually enter the battlefield - it didn't change zones, it just changed from one thing to another within a zone. So no, it doesn't trigger evolve.
As for citations, well, there's a ruling explicitly for this land-becoming creature case on many of the lands that can become creatures (e.g. Celestial Colonnade):
When a land becomes a creature, that doesn't count as having a creature enter the battlefield. The permanent was already on the battlefield; it only changed its types. Abilities that trigger whenever a creature enters the battlefield won't trigger.
I don't think the comp rules really say this explicitly; they say the battlefield is a zone, and "entering" a zone clearly means coming from outside the zone into the zone. For example, there's stuff like this:
110.1. A permanent is a card or token on the battlefield. A permanent remains on the battlefield indefinitely. A card or token becomes a permanent as it enters the battlefield and it stops being a permanent as it's moved to another zone by an effect or rule.
603.6a Enters-the-battlefield abilities trigger when a permanent enters the battlefield. ...
Nothing explicit, but consistently "entering" a zone is used to mean changing zones into that zone.
When you animate a land (or more likely in this case, an artifact), you are merely changing its characteristics. Tower Defense also changes an object's characteristics, yet you would never say that causes the affected object to enter the battlefield. That's because changing an object's characteristics does not cause the object to enter the battlefield.
To be considered to enter the battlefield, the object must do exactly that, enter the battlefield from another zone. Standard English definition applies. If the object was already on the battlefield, how can it possibly be entering it?
