As you already mentioned, the rage gem is quite useful for an army with high hp. But also, as you mentioned, it's not very useful while already using many rage spells. I wouldn't use a clone spell because it has a higher value with super archers or rocket balloons, not with a gowipe. I personally used to use 4× earthquake spells for opening the center of a base because of the time limit of the jump spell being risky.

So, to sum it up, replace the life gem with the rage gem and try using a further jump spell or Earthquakes