The Conjure Lesser Demons spell states:
The demons attack the nearest non-demons to the best of their ability. As part of casting the spell, you can scribe a circle on the ground with the blood used as a material component. The circle is large enough to encompass your space. The summoned demons cannot cross the circle or target anyone in it while the spell lasts.
Is the creation of the circle magical in nature? Could the party Fighter, in order to protect him/herself, create a circle of blood that would ward off the demons?