@Ed0517
Maybe he can link to Mouse's ice world - Mouse was an ice demon, right? Mouse cheats by living with a wizard - he channels his power source thru Harry.
Is a foo dog an ice demon? I don't understand? Honestly I don't know much about foo dogs, is this somewhere in the books or side stories?
I can follow you explanation of power levels. Yes, this is how one can imagine it.
But I don't think, he calls ectoplasm. In the books it is often described that he reaches inside, fuels his spells with his emotions and sometimes he explicitly takes from his surroundings.
This is just my head canon, but I think it is the magic itself as a kind of substance which a wizard can use and transform with his will. Not something from the nevernever.
Why can't it be ectoplasm? Because ectoplasm evaporates and there is never any goo left after a wizard does magic, except the times in Peace Talks when he sneezes ectoplasm things.
Also Harry often states, that fire is hard to controll, because once it is there, even magical fire, it behaves like any fire does.
Then there us the difference between magical fire and mundane fire. I think the first mention was in Ghost Story, when he remembers his fight with the Walker and uses his first fuego to kaboom the gas station. Good that he didn't directly use it on the Walker, because in Peace Talks (the fight against the cornerhounds) Ebenezer tells him that Outsiders are somehow immune to magical fire, and that he has to use mundane fire to hurt them.
So I think, a wizard's spell is made of magic transformed into what the wizard wants it to be. Be it force, fire, water, ice...
He yanked water out?
Exactly. Removing water imho is what Carlos' shield does. I think it is even somewhere in the text, I might look it up later, or maybe someone has it handy before I do.
Actually used this way, water magic can be applied very powerful. Have you read the Alex Verus books? There is one wizard, Rachel (she is crazy and doing a lot of morally compromised stuff), ewho does exactly that. She can remove water from any target, essentially turning it to dust. I think this is what Carlos can also do. I think this is what he does, when he fights. Harry sometimes describes it as a green ray (hope I can find example, too), but there is never a description what happens to the targets. Probably because usually Harry has no time watching closeely during a fight.
Ice magic as winter knight: I think Harry reaches for the Winter Mantle to do it other than taking heat from water.
Sadly there is not much explanation in the texts as to how exactly magic works.
I think of it as some sort of catalyst, that some people have inside and some don't. Some have much of it, some only a little bit.
The catalyst takes either from inside the wizard and/or from the surroundings to amplify whats already there, depending on the source the wizard prefers for his spell.
