The idea behind magic in general, no matter what it looks like, Isn't turning "Nothing" into "Something". The idea is turning "Energy" into "Matter" or into a different form of energy. All concepts of magic work on this principle. When someone throws a lightning bolt, they turn "Life" energy or "Mana" into Plasma. When someone uses "Creation" magic, they turn that energy into "solid" matter. 

When you're creating a magic system, or even just a single spell, your question shouldn't be "Is this allowed" it should be "How much energy does this take?" "Where does that energy come from?" and "What happens if you use too much?"

you've already answered the "Where" and the "What", now you just have to answer "How much?"