To deal a large amount of damage you have to perform a combo. There two, three, four and five-hit combos and each are executed by swiping in specific directions.

Two-Hit Combo:
Two hits in opposite, non-diagonal directions. Example: Left, Right.

Three-Hit Combo:
Three hits in the same direction. Example: Left, Left, Left.

Four-Hit Combo:
Two hits in opposite directions, followed by two hits in the two remaining directions, excluding diagonals. Example: Down, Up, Left, Right.

Five-Hit Combo:
Two hits in the same direction, followed by two hits in the opposite direction, followed by one hit in one of the other directions, excluding diagonals. Example: Right, Right, Left, Left, Up.