What can they do? Are you able to stop your opponent's movements with them?

True. Each world seems to have their own version of magic and how they use it. I've never though about a magic that relied on will power.

Ah, the reason behind it sort of goes into my world's history. There was a King who did and was reborn as the King of the Wind. He traveled the heavens with the Summon Spirit known as Past, Present, and Future who are now known as the Summon Spirit Sylph.