What is a booster?
A Booster is an element that can be used to make completing a level easier.
What kinds of boosters are there?
The Ice arrow collects two rows of potions.
The Fireball removes one element from the game field. Elements which have several stages of transformation in interaction with the Fireball move to the next stage.
The Tornado helps to interchange places of a Potion and a Super potion.
The Lightning destroys all potions of one kind at your choice.