Level 21 is the eleventh level in Amber Alley and the ninth Firefly level in Diamond Digger Saga. To pass this level, you must wake up 1 firefly and reach 2,500 points in 10 moves.
There's very few moves, and often there are no possible moves except those that don't give you any progress. First really dumb design, but there are many more to follow!.
You have rockets - it's most likely that the one at top left corner won't be usable, and also it's very likely that the one at the top right corner won't be. Use the one that you can match. Afterwards, focus on destroying the required ground blocks, so that you can bring the flow of water to the firefly, your target.
The 1-star target score used to be 4,000, leaving a possibility of failing the level with not enough score, although it is uncommon.