I've still got mine, and I don't plan to use it for a while. C: I'm going to catch all the legendaries apart from Latios first. I've got Entei, Raikou, Suicune, Ho-oh, Lugia, Zapdos, Moltres and Articuno so far, and I've got Groundon, Mewtwo, Rayquaza and Latios to go. My method being, the other day my boyfriend asked me, "If you saw a shiny legendary, would you use your Master Ball on it?". I know the chances are ridiculous, but I'd hate to end up KO-ing/losing to a shiny Legendary, or runnning out of balls, and knowing that if I'd just saved my Master Ball, it would've been mine. C: If (more like 'when') none of them are shinies, I'll use it on Latios, because I think the Eon duo are worth it. C':