Completion

The separated space within the cauldron disappeared one after another, while Alex let the energies mix into each other at a certain rate to get the reaction correct.

There was a reason why he didn't make the previous pills in this way when this way was clearly so much faster. The energy had to be mixed artificially on its own later which was much more difficult when one had to do it on a much larger scale because of the amount of energy one had to control and mix together.

It was better to let such things happen organically by following the original pill recipe.

But for a single set of ingredients, Alex had no issue at all. 

The two energy from two different ingredients mixed and then Alex removed another separated space, the energy which mixed with the other ones. One after another, as the space disappeared, the resulting energy was advancing toward what would make the pill.