The way Plarium have designed the metrics, all of my cities make Moonstones faster than I can use them.

Offering me a reward of 10,000 Moonstones is of absolutely zero value to me.

Whats is challenging is keeping stocks of GP's filled so that I can use the moonstones to build more E.troops.

Solution: change the reward for this daily challenge from 10,000 Moonstones to 100 GP's (that is the quantity of GP's 1 need for me to build E troops each day - un-boosted!).