(IT IS HEAVILY RECOMMENDED TO USE THE MOD "JEI" WITH THIS MOD!) This mod is also NOT FINISHED!)
This apocalypse mod adds a new mob- The Silencer:
The silencer works a lot like the Death Angels in A Quiet Place- They hunt by sound and can hear you from 100-2000 blocks away depending on what you do with different levels of the "Sound Emitting" effect.
Silencers are nearly unkillable and do insane damage, able to oneshot the player along with the fact they are insanely fast. your only option is to be... Noiseless.
But this mod doesn't just add the silencer, but also adds many new structures and weapons.
Enjoy :D

