Charlie's here...
Information:
Charlie is the name of a mob (show in the image) who will constantly search for players nearby to kill (Only in the overworld). Charlie is able to track players from far distances and almost impossible to kill. Running away is advised.
(Requires GeckoLib)
Mechanics:
Charlie will spawn near the player when the world starts as a invisible mob. While Charlie is invisible, it will wander near the player but will not attack no-matter what.
When Charlie is visible after a certain amount of ticks, it will select a random player in the overworld nearby as attack target. At this point, the target might or might not hear cave noises or Charlie "laughing."
Charlie will chase the player at all cost, even ignoring other mobs in-order to kill its target. Charlie is able to climb blocks similar to spiders, and can break certain blocks such as glass or door.
After a certain amount of time, Charlie will automatically despawn, and respawn near another random player as a invisible mob. The cycle will repeat itself in-game.
If Charlie is killed, he will respawn again.
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Feel free to use this mod for your modpack or server.