Depending on whether or not you're publishing it or not will decide whether you "should" use it.
If it's a personal book/school report, then by all means, go for it.
If it's a book that you're planning on publishing, you should either make your own design up, or talk to the game developer. If you use the symbol, without getting around the copyright issue, you could be in for some trouble
maybe if you change the color/armor itself and turn it into another creature with a different background, maybe, talk to him and try to differ it as mush as possiblew