Usage patterns
〈事〉の呪文を唱えるto chant/recite a spell
The wizard chanted a spell and put the enemy to sleep.
〈人〉に呪文をかけるto cast a spell on someone
The witch cast a spell on the prince and turned him into a frog.
呪文が効くfor a spell to work/take effect
The spell took effect right away, and the room became bright.
呪文を解くto break/undo a spell
The hero broke the old spell and saved the princess.