Mirran Mettle * I don’t recommend metalcraft.

This card does not have much to offer.  +2/+2 is practically worthless.  And, I have never been successful at using metalcraft.  That is if you have 3 artifacts out, then you have probably  spent too much mana, or too much of your hand size, or too much of your deck in order to get all 3 on the battlefield.  There are simply too many ifs when using metalcraft.