The investigation of the Ora Ignimbrite (~275 Ma) helps further our understanding of how vast amounts (>1,000 km3) of melt are generated, stored, and erupted from the shallow crust. As the last eruptive product of a slab rollback ignimbrite flareup that lasted for 10 Ma, Ora’s glacially incised outcrops tower over 1,300 m above Bolzano, Italy. Two key outcrops, early-erupted intracaldera vitrophyre and late-erupted outflow vitrophyre, provide well-preserved, glass-bearing juvenile material. Petrographic optical and electronic (back-scattered electron) analysis was used to document the textural features of minerals and glass. Glass and mineral major-element compositions were obtained using Energy-Dispersive X-ray (EDX) analysis on a Scanning Electron Microscope (SEM). Glass with low Na/high K concentrations and A/CNK ratios > 1.1 was deemed altered. Intracaldera vitrophyre contains two distinct fiamma types: very coarse-grained, crystal-rich (VCCR) and fine-grained (FG) fiamme. Glass in VCCR fiamme is homogeneous high-silica rhyolite (76.5-77.5 wt. % SiO2; normalized anhydrous) with low K2O values (3-3.5 wt. %). The FG fiamme have a broader SiO2 range (75-78 wt. % and 72-78 wt. %) and higher K2O values (3-4.5 wt. %). Outflow vitrophyre has medium-grained (MG) and fine-grained, crystal-poor (FGCP) fiamme. The MG fiamme have homogeneous high-silica rhyolite glass (76-78 wt. % SiO2) with lower K2O (2-3 wt. %). Glass in three FGCP fiamma form compositional continua from 68-78 wt. %, 67-79 wt. %, and 72-78 wt. % SiO2, and K2O varies substantially (0.5-3.5 wt. %). These results demonstrate mingling and mixing and suggest that multiple melt-rich zones contributed to the erupting magma. We propose that at least four separate magma bodies contributed to the Ora eruption. Each one evolved independently, leading to variable amounts of magma mingling and mixing. These results illuminate the subsurface architecture of a large silicic system during the final episodes of an ignimbrite flareup.