Describe the processes that turn metamorphic rock into igneous rock and the energy that powers the processes.

So, we know that a metamorphic rock is either an igneous or a sedimentary rock that are exposed to intense heat and pressure.

But when the metamorphic rock is thrusted deep underground through subduction, it will again be subjected to intense heat. This can cause it to melt, turning it into a magma. When the magma cools down, it again becomes an igneous rock and the rock cycle continues.