I completed this level with a total of 0 moves left on my first try. I would suggest bringing the following fiends along with you mainly to help you out: Brittle (Purple/mushrooms), Gene (Green/leaves) and Kwincy (Yellow/flowers). They may not seem powerful but your main objective is to collect the resources and not defeat slugs. Defeating slugs is optional. This can be a tough level but once you practise, it can become much easier. I had also used gold bars for extra moves but with one of my tips that I said above, it could help you out.

Diane Dickerson - You can get extra gold by either buying it from the store (it's best to wait for a sale, they come regularly), You can also win free gold special year events like Halloween. In the Halloween event you can earn gold and diamonds by defeating a certain amount of slugs.