Board Thread:Questions and Answers/@comment-16909581-20130830181431/@comment-24145588-20131206234716

I would go with the new island. I'm still building up my Cold Island, but I've bought Air and Water, just as a place to put more mines and ovens. The castles there are small, each just upgraded once, so I am not placing many monsters there yet, but it does allow me to farm 3-element and 4-element monsters on those two islands, just for added cash.

The 6.5M gold for the first castle upgrade on the Water Island was a nuisance. The second castle upgrade costs 7.5M, and for the same price I can get the Earth Island, so the next time I save up for something big, it'll be the Earth Island. I'll have another mine, more ovens if I need them, and another hatchery where I can breed monsters for cash.