Dark magic

For the player to be able cast dark magic they'll need a corrupted spell book, which can be obtained in a woodland mansion. This book contains different items and what they cast. The player needs to have the book in their off hand to cast dark magic and the object needed for the spell in their main hand. The player will then have 3 area, self, mob. Mob will cast the spell on whoever the player is facing, area will effect every mob in a 5 block radius surrounding the player, and self will effect the player. Here's an example just in case I'm not making sense. Holding the corrupted spell book in your off hand and rotten flesh in your main hand will allow you to cast hunger on yourself, the mob that you're facing, or mobs in a 5 block radius.