theory11 — Magic Tricks & the World's Finest Playing Cards

What is this effect called?

That is just awesome..how did he do that man..really very impressive..thanks for sharing such a nice post out here..i really appreciate that..although i wonder when is more in coming?
 
A very promising start, but he definitely goes way overboard trying to be 'crazy' and didn't really choose his effects to enhance that idea.

I'm not sure about the trick. I assume you mean the card visually changing into another one? Looks like a variation of Aura.
 
I saw this video the other day and I really enjoyed the character though I didn't really care for the cheesy mad scientist costume at the end. I think Christopher is right about the trick being a variation of Aura (it's sold by Ellusionist if you want to go hunt it down). It does seem to use the same method.
 
He was actually one of the first magicians I ever saw (on TV, not live) but totally forgot about him because he kind of disappeared for a while. The Coolest Magician on the Planet or some such. I liked him. The four-leg thing has always stuck in my memory.