The biggest problem with clouds is that you’re never going to get them to show up when you need them to. There’s often a level limit on clouds, and if you have clouds on the left then you’ll need to clear dots on the right to get more.
Clouds can be destroyed with erasers, bombs, gem blasts, or other cloud zaps. However, the primary way to clear clouds is to put two of them on the same row — the moment there are two (or more) clouds on the same row, they’ll zap themselves out of existence.
A cloud zap will hit slime, ice, balls, or beetles one time, no matter how many clouds you clear on a single row. One zap will also clear an anchor or all the background from cloud to cloud.

Level 776: five clouds, each of which has slime behind it, hemmed in by trapdoors. There’s also water. So this level is pretty complex.

Level 778: you can see where I cleared two clouds, and the remains of the zap. There are so many bad screenshots of this on my phone that I may have filled my SD card.
Strategy:
Clearing clouds is all about making sure you get enough of them to meet the goal. It’s much easier if you do this at the top of the screen than at the bottom. However, if you have other goals to meet, you’ll have to decide what’s most difficult — and this may take a few tries.
Remember to balance your clouds on the left and right sides so that you don’t waste moves generating them.
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