Board Thread:Game Discussion/@comment-36550098-20180811185257/@comment-27798333-20180812135227

You do that cloud save(s). Then you can buy the upgrades. See what PR you get. If they don't add up to what you want, or need, restore your previous save. The recent upgrades go away, and you get your gold back. Then you can try other upgrades to see if another combination gets you where you need to be. As long as you keep restoring, you never commit to the purchase, and you never lose any gold.

That's what they mean buy testing the combo.