As others have pointed out, Elements is in the same genre as MtG (note, that is a genre which was created/became popular by/through MtG), but not a rip off. I’m not talking about the artwork here, but mostly about the game mechanics. There are definitely enough differences for Elements to be called an original game.
Here is a nice article by David Sirlin on what are rip-offs and what not, and on why we should be careful not to mix those. The main point is: If people call games, which are similar, but add original ideas leading to a different gameplay, that stiffles innovation and prevents better games from developing or becoming popular.
For some reason I always was thinking that Zanzarino created Elements as a homage to Magic? Is that just my imagination, or has someone heard somthing similar? That might explain the similarities.