It doesn't copy whether that creature is tapped or untapped, whether it has any counters or stickers on it, and Auras or Equipment attached to it, or any non-copy effects that have changed its power, toughness, types, color, and so on
It's a little special, but since Darkness x2 and materials are loose, you can put it out just by inserting a fusion gimmick into various Darkness Decks, and it can also be used as a super fusion agent
But it was a good idea for Arena to not introduce them right away - it took me a while to unlock my first dual deck, and by then I had a better understanding of each mana colour
House, using a variety of dual lands and mana rocks
Seven mana for a 5/5 isnt good, and giving it forestwalk reduces its power and has an extra mana investment