Alex focused on his spiritual sense, using it to magnify into the powder in the cauldron, but there were too many to focus on.
He couldn't possibly join all of those powders right now. At least, not with the level of spiritual sense he had right now.
He could focus on multiple of these at once, so he decided to start with that. No matter how impossible it looked, he had to try.
So, he started doing it. He went around the cauldron, trying to find the individual specks of powder and brought them together. He moved them, twisted them, slid them into places, and finally managed to make a clump of the powders that perfectly fitted together.
His eyes beamed with joy, but then immediately dulled as he saw the other many individual specks he had to get to.
He sighed and got onto it. He split his concentration, putting all of his focus into the cauldron, and started fitting the other pieces together.