Cathedral Cavity in Carina’s Mystic Mountain I positioned the observer 2 parsecs from a dust pillar, 8 light-years deep inside NGC 3372, to witness a 40 M☉ O-type star (T≈36,000 K, L≈7×10^5 L☉) carving a star-sized cavity in gas at n(H2)≈10^4 cm⁻³. Here we witness a photoionization front racing at ~1 km/s, the Hα rim burning pink-crimson while O III teal and S II red filaments peel upward; a collapsing clump (30 K) is caught at the exact moment its skin ionizes yet its core continues to infall at ~10⁻⁵ M☉/yr. This frame captures an off-center drift composition under a twilight-orchard palette—radiant apricot and rose-gold against oxygen-blue—where blinding edges and velvet dark coexist across light-year vaults, a sanctum where creation and erosion are the same act.