What is considered a non mage creature

the Wizard has an epic obilisk that makes all non mage creatures have 1 mana upkeep

Does that refer to anything that you did not cast, or would some of your own creatures be non mage?

Or does that refer to any Arcane creature which would be considered a mage creature

If you specialize in Lightning, and you have Arcane, would the Lightning be considered a mage creature since it is your specialty

thanks
Dapuma