Bubble Witch Saga Eternal Isles 21 Level 3
At EI 21-3 you need to have a bit of luck or the Charm of Antidote if you want to drop as many bubbles as required under the viruses to get to do bankshots via both walls to drop the big pyramid of skulls by shooting above it.
I prefer to shoot down at least one virus cluster completely. In the video attached it is done by aiming two rainbow Bubbles above the right side virus cluster, but if you need your RB Bubbles for something else you can also first shot as much below the viruses, so that you lower the screen to see the colours above them to either screencap or memorize. Then shoot bubbles to attach themselves to either side virus to highten the screen again and aim above them to drop the virus cluster. (See Pic attached)