[@Narcotic Dollie] Un/Fortunately, Kelvin is completely unable to interact with physical things except by magic- even his sword is a ghostly construct of the original... (he couldn't stab someone if he wanted to)

The GM mentioned that the opposing types of magic could knockvout various beings though.
[@Ace of flames01]
I guess in this case, an aura shield would be like using your own magical power as protection against another magical attack- surrounding yourself with your own power for protection. It likely would have the same cost as the blocked attack required to use. (Nonphysical protection)