Understanding the subsurface conditions and dynamics of magma is key to mitigating hazards and environmental impacts of volcanic eruptions. Observable and measurable precursors of eruptions (e.g., degassing, tremors, edifice deformation) and information from melt and fluid inclusions, minerals, vesicles and glass in erupted products can be used to decode the storage conditions of multiphase magma in reservoirs and its transport processes in volcanic conduits during eruptions. Constraining magmatic processes and parameters such as volatile degassing and outgassing rates, kinetics of magma crystallization and vesiculation, multiphase rheology and fragmentation of magma is important to better understand eruption conditions at active volcanoes and magma reservoirs. This session aims for a broad and interdisciplinary scope and invites contributions investigating the plumbing architecture of magmatic systems, their physico-chemical evolution, and measures to understand and forecast volcanic eruptions using field observations, laboratory analyses, experiments, numerical modeling, geophysical and geochemical techniques.