The Stone Walking buff is an artifact buff applied by the Ring of Stone Blood. It is a doom buff that triggers a special death condition when the hero dies while affected by it.
The Stone Walking buff allows the hero to traverse walls as if they were open space. The hero's blood turns to stone which merges with nearby walls, making traversing them much easier. However, this power comes at a terrible cost - if the hero dies while affected by this buff, they are permanently immured in stone.