Archaic spear

You form your magic energy into a a long, sharp rod of arcane energy.This rod is very unstable taking on different damage types if not kept in control.The rod of arcane energy is normally a fire damage type if kept in check.The spells damage modifier is 1d12 and it is shown as a beaming hot magma-like rod floating in the air radiating immense heat.The target must make a Dex save of 15.