Rock of Ages 3: Make & Break

This is easily obtainable in the tutorial mission right after you start a new game and get past the part with the sheep ball hitting the boulder to open up the cave. Right after this part, you have to defend your gate from oncoming boulders of all sizes. Build up your defenses and when you see a small boulder around half health, go ahead and zap it with your lightning ability. If you fail once or twice, just keep at it. There are quite a few small boulders in each of the 3 waves of the tutorial.