On a build a couple months ago I built a bunker that had a 30 degree egress. This then led to a tunnel with traps and iron bars for easy shooting. It funneled all the zombies into a kill zone. It was good for awhile but not as successful as the above ground killing corridors.
My current horde night defense is a three story building with the main level 3 blocks high. Surrounded by spikes with a pit in the center that is also covered in spikes. To exit is a drawbridge that goes over the pit. Solid walls cover the interior and iron bars on the exterior in a platform and wall combo with 1m of concrete wall to stand on since it is more durable. Second floor is the crafting area with an area that perches over the drawbridge. Top floor is the garden.
Every horde night the zombies ignore the pit of spikes and go for the walls. This will get more complicated with zombie vomit going through bars and the demolishers but it has been pretty effective with a 2 person team.
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