This mod allows to spawnproof areas of 64x64x64 blocks with just one end crystal (cubic, not spherical).
Each crystal you place in the world creates an area that starts from the block it is placed to 64 blocks above vertically and 32 blocks in each horizontal direction (north, east, south, west). This is mainly because it is easier to hide it below the surface you want to spawnproof.
The original idea of this concept is made by ethnographie and you cand find her datapack here.
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