I’m Just a Food Delivery Guy. What’s Wrong with Striking Ghosts with a Thunderbolt Curse?

[Brain + Supernatural Investigation + System + Invincibility + Crazy Practice]

How did I, a delivery boy, go to the wilderness to deliver food?

What's wrong with me wearing a yellow robe and being able to cast spells?

I've never heard of clearing out C-level ghosts. I don't know how to kill 200 ghosts in one move.

Stop talking nonsense with me and hit me with the Heavenly Thunder Curse of the Jade Emperor!