Use all 4 potions.
You need patience and luck for this one.
Clear the bubbles on the left under the first chain so you will have a clear shot under the first bomb that will start counting down when you unlock the chain. (You will need luck to have the right colored bubbles to drop it.) Then clear the bubbles on the right under the second chain so you will have a clear shot under the second bomb that will start counting down when you unlock the 2nd chain. Finally, do not unlock the second chain until you have dropped the skulls; otherwise, you will not be able to see the ticking bomb. You will probably need to use a Rainbow Bubble.
Screen Shot of the level:
Bubble Witch Saga is a free game and puzzle! Along with the rules, we have free coins, videos, tips and tricks on our All Help Group website. Join our Group on Facebook for interactive support and fun for members!