Then go to:
http://sdb.drshnaps.com/game.php?game=861
There, you can find all of the available Card Fighters Clash cards.
When I did my Magnus card I used this card:
The changes I did on this pic:
1: Erasing that annoying lighting arcs.
2: I change the colors of his hair, coat, etc.
3: Redraw the coat to look like shoulder plates, drawing the eyepitch, and such.
After that I noticed that, there's something missing from this picture: a weapon. I think the foecleaver of Magnus is too big to fit, such as his boomstick, so I choose the Mechanikal Arm. I've searched a new pic that contains something like that, and I find this:
I cut the glove from this picture, change the colors to something more metallic, and I put the Rugal picture above that. At last, I made some background, and the "Asheth Magnus" sign and voilá. If you can use the Paint, you can do this. I hope I can help.