The Reason
To increase the effectiveness of the spell, he first began with the basics of it.
The basics weren't hard, as all the foundations for the spell were something he had known for a long time, and he just had to learn how to create a perfect equilibrium with them.
With some time in hand, he knew he could do that, and that's exactly what he had done.
After perfecting the basics, Alaric began to learn how to produce as many tentacles at a time as possible. This part was the second most difficult thing to learn about this spell… but he had done it as well.
Having achieved success in creating hundreds of tentacles at a time, he then began to learn how to command them separately. After experimenting with this, he found that commanding hundreds of tentacles was a bit challenging at this moment, so he moved to the next best thing.