Question

A __ is a tall block of souls stone standing by its slef

Answer 1

It sounds like you might be describing a "soul sand valley" or a "soul sand" pillar in the game Minecraft. In Minecraft, soul sand is a block that can slow down players and mobs walking on it. However, a tall block of soul stone by itself could also refer to a "soul lantern" or a "soul campfire" if it were placed in a specific way or context. If you're thinking of a specific structure, please provide more details!