I've been trying for the Memorial and Marine monsters for quite some time now. I'm starting to think I'm going to miss them. I've been trying with Earth and either Freeze or Icefloe. I figure this way I can get either of them... Memorial or Marine. But so far, no luck. I've tried the basics too... but these limited edition monsters are very difficult to come by. It makes the game a bit... unfun. I don't believe in spending 'real money' on games so it takes many hours to try and fail over and over. If I wanted to spend money, I could quite possibly spend hundreds easily! Oh well, I'll just have to keep trying and failing until I actually succeed or the monsters are gone until next year.
Keep moving forward,