This trick can be used in your game...

Yes Blackburne Shilling trap, very nice. But white is doing well after 4.Nxd4.

After N×d4 on 4th move. Then to after exd4 it is not too bad position.

Black can still led this position..... 

It is better for white, after Nxd4 exd4 the black pawn on d4 is over extended and white can take over the centre. This ancient trap is very cool, but the problem is exactly that - it is a trap. If the white player knows it then black is in a bit of trouble. If you're playing for fun in blitz or bullet then sure no harm to play it. But if it's a game that you are taking seriously better to play normal lines of Italian game and fight for your chances. 

I agree with you

But this opening is playable

I came across it once. Ignored the pawn and played c3 to kick the knight out. We exchanged on f3, taking back with the queen, and I had a huge lead in development with d4 nicely prepared. Wasnt very impressed with it. Seemed like a waste. Black should just develop normally.

That describes just about... every opening? Heck, there are players that are winning with the Bongcloud.