Which intrusive feature may start as a sill but, as more magma builds, it pushes upward like a lens

An intrusive feature that starts as a sill, but build up with magma into a lens-like structure is a batholith. A batholith is composed of igneous rocks due to the hardened magma from the Earth's crust. The opposite of sill, dike, builds up to form a laccolith, another intrusive feature with a mushroom-like structure.