Reinforced deepslate forms the frame blocks of the portal structure found at the centre of every ancient city in the deep dark biome. It has a blast resistance of 3,600 — three times higher than obsidian at 1,200 — making it effectively indestructible in survival gameplay. Even a wither skull direct hit, the wither's dash attack, or a charged creeper blast cannot break it.

The block cannot be crafted, smelted, or obtained through any in-game recipe. Silk Touch does not work; the only legitimate way to obtain it is through creative mode or commands. This intentional uncollectability preserves the structural integrity of ancient city portals and prevents players from dismantling the frames they protect.

Its dark grey textures share visual lineage with regular deepslate but feature reinforcing bands across the surface, giving a distinct industrial appearance. Server administrators and map makers use reinforced deepslate as a true grief-proof building material — any block that cannot be blown up by TNT cannon or wither farm is practically untouchable.