Many people may be familiar to this spell which is called Stupify. This spell makes your opponent shocked, almost like an electric shock for a long time. This will might be difficult for some people but like a said before, practice makes perfect. This is one of my favorite spells because it would come very useful in a powerful duel with a dark arts master. Just so you know, it took me a long time to master this spell and to get the movement correctly the same, but if defense against the dark arts comes easily for you, you might learn this spell quickly.