This multidisciplinary symposium in memory of Prof. Leonid Perchuk is aimed to bring together scientists working in diverse branches of petrology, geochemistry and geodynamics, covering major problems of magmatic and metamorphic petrology related to geodynamic evolution of the Earth’s crust and mantle. During his very long and extraordinary productive scientific life, Leonid made outstanding contribution to these three branches of modern geosciences. Therefore, we intend to subdivide our session into three sections. The section “Magmatism” will include contributions concerning new researches on magma generation and fluid-magma-host rock interactions both in the mantle and in the crust, experimental and numerical modeling of magmatic systems within a wide range of P-T conditions. The section “Metamorphism” will involve presentations covering the problems of regional metamorphism, including granulite-to-greenstone belt relations, HP and UHP metamorphism in subduction zones, role of fluid pathways and deformations in metamorphism, dating of metamorphism, and experimental studies on phase transformations and metamorphic reactions. For the section “Geodynamics”, we inspire experts on numerical geodynamic modeling, structural geology, and tectonics to present their recent studies on how phase transformations affect geodynamic processes and how natural observations and experimental data on phase transformations can be used in solving geodynamic problems. No doubt the above sections are highly interrelated, and this mutual connectivity will help understand how our planet works. This is the task, to which Leonid Perchuk had dedicated his outstanding scientific life.