I got a really awesome idea that every player will love and that will fill your goblin money sacks!
Introduce a special really strong unit called the Flaretroll that costs gems to spawn instead of morale. Maybe many won’t like them or use them but the top alliances will have to use them to stay top so thy could even cost 100 gems per unit.
To spice it up even more make a new tower type that we can spawn at max level but costs gems per hour you have activated. This tower must be so strong that in order to beat it if many enough are used, you must use the Flaretoll to have a chance .
That way people will spend alot of gems to be in the top ranked alliances since they will need both the towers and the units to have a chance
Also a you might want to reduce the gold that people currently can raid by 80% it’s to easy to get gold now. Introduce the Flaregoblin! Similar to the Flaretroll he must cost gems to deploy instead of morale.
What makes the Flaregoblin special you may wonder? If it reaches the enemy gate he will increase your gold bonus by x % per unit that reaches it (or even better just write increases gold loot by a random number that no one understands). Players will have a sensation of getting alot of gold but basicly they will now spend gems to get the same gold as they were able too before without realizing it! Some will but the majority will be blinded by how cool it is with new units so they won’t even notice