A sunken library boss arena in Mine...

A sunken library boss arena in Minecraft voxel style, wide shot from the entrance arch. A square deepslate-brick hall, 32 blocks wide, with teal prismarine trim bands and sparse sea lanterns in a dark ceiling. Dark prismarine floor cut by water canals in a + shape plus a perimeter moat — still, faintly glowing dark teal water. At the center, a raised stone dais carved with a glowing teal magic-circle inlay. Four thick stone pillars with soul lanterns stand at the diagonals. A bookshelf-lined mezzanine balcony rings all four walls at half height, with hanging lanterns beneath. One grand arched doorway. Dim, cold, drowned-library mood — cyan-teal glow is the only accent color. Empty, no characters.