The impostor addon adds a sus impostor they naturally spawns in the world. The impostor does a massive amount of damage and is a great addition to mob farms. The sus imposter has only 1 hp, but don't let that fool you, his damage makes up for it.
Where will it spawn?
The impostor will spawn in light levels of 7 or less. He is less common than normal monsters so you will have to try a little harder to find him!
What does it attack?
The impostor will attack all passive mobs, hostile mobs, and players! Be warned as the impostor is faster than a normal walk speed!
Installation
Double click on the file to open it and Minecraft and then enable all experimental settings and enable the add-on under the behavior tabs.