In the minecraft 1.17 update there is a new mobcalled the warden. It spawns in the new biome dark caves. It is blind but it can sense movements like a player walking or a snowball hitting the ground. Also all lights willl flick on and off when the warden is near it. You could say it is the boss of the overworld becasue it has 95 health. You may ask what does it drop, well it doesn't drop anything but it guards wireless redstone which senses movement. Like say you place a block of tnt and the wirless redstone on top, when a player go 10 blocks around it the tnt will explode. It's good for making traps.