Factory + Blood Moon

[TheCramp]

This happened today, and we had to put aside the game because we didn't know how this worked. I didn't see it in this forum, so I'll add it since the cards are so commonly played.

If my opponent drops a bloodmoon, and I activate factory in response, will it be a 2/2 mountain creature by his attack step?

[Anusien]

A 2/2 artifact creature land - mountain assembly-worker.

[mujadaddy]

No. The factory will be a (nonbasic) mountain.

Once the blood moon is in play, the factory doesn't have its ability anymore. So the only way that it can be activated the factory turns into a critter, and then into mountain since the factory's activation resolves before the blood moon comes into play.
Blood Moon changes the LAND to a mountain, but as long as Factory is activated in response to Blood Moon, you'll get your 2/2 Artifact Creature Mountain... until end of turn. Afterwards, it's just a mountain with no abilities to activate.

That is...

Announce Blood Moon.
Activate Factory.
Factory becomes 2/2 Artifact (Assembly Worker) Creature Land.
Blood Moon turns the land into a mountain.
Factory becomes 2/2 Artifact (Assembly Worker) Creature Mountain.
EOT, Factory becomes Mountain.

[Anusien]

Blood Moon changes information about one type (Land). It doesn't affect the other two types (Creature and Artifact). You're right that Blood Moon applies last in Layer 4, but you missed that the Factory's P/T applies in 6b and that changing information about one type doesn't affect the other types.