{ diluc may be talking to himself, but thankfully he's loud enough that anyone in the vicinity can hear. sonia has only been here days at this point, but she's already making headway with the magic here after already learning some back with audentes. not to mention the company she kept back home.

besides, there's something with the wording they chose to describe this that makes it possible to make an assumption on what they have to do. }

Are you familiar with choirs or groups of singers? When they all sing in tune together, that is in 'harmony'. In this case, I imagine it is managing to ensure the flow of magic is similar enough that it harmonises, rather than one overpowering the other.

{ she gives him a smile. }

Would you like to give it a try?