It was the main characters idea of how to restrain his opponent at the time. In the book though had he mentioned that idea before hand the physicist would have said “you know that will disintegrate them right?” Or upon his return to the as yet unnamed home base and told the group what happened the physicist would’ve looked at him like he’s a dumbass and said “I could have told you that was going to happen, now we have to track down another one to extract information from.”
Oh, I forgot to mention, this story is taking place in the present with all available technology. I decided, for my first time writing, that it would be easier to operate in a world already built.
To, in a round about way, answer your question the laws of physics do affect magic and messing with them can have terrible consequences.
Actually I was being literal.
If you have an object in the center of the room that is absolute zero the physics reactions would be horrifying.
1. The air would hit that point and crystalize.
2. Consider the explosive impact of water instantly becoming steam. Now reverse that and multiply by (I have no idea how many multiples). The type of elemental state change (directly from a gas to a solid) would be unbelievable.
3. The type of physical implosion in the space would be staggering. The suction would tear apart most buildings.
4. Anything that is sensitive to sudden air pressure changes within the "blast area" would be destroyed - such as living things, ears, eyes, plant tissue, flesh.
5. Whatever this zero temperature object was in physical contact with would instantly freeze. The floor for example. Even concrete will freeze and become brittle. When struck by the objects sucked in by the implosion all of the brittle surfaces would shatter - especially the person you froze. If you were on an upper level of a building the floor would simultaneously freeze, experience massive suction and be struck by the objects sucked against it. How long does this reaction take? (I don't know) but a guess would suggest how many floors would be destroyed.
So, not so much an abstract idea but the literal effects of such a temperature change.
But, if you are thinking about basic Newtonian physics, from whence does this massive amount of energy come? How many giga-joules of energy is this? Enough to bring that size object to absolute zero degrees would be
something to look up. The Heart of Gold (Douglas Adams) was supposedly powered by tearing apart stars. Your example requires an amount of energy that would be noticed. Does he generally reduce the temperature of the planet by a degree or so? Maybe all the ambient energy (heat) from the immediate area causing snow across Western Europe in August perhaps?
Fun fact, In building science it is well recognized that all energy added to a building ultimately becomes heat. Respiration, your computer, that little blue light on your charger, the microwave oven clock. There is a joke that electric lights are simply inefficient heaters since some of the energy becomes light before it becomes heat. Ambient energy is generally felt as heat.
That could be a methodology for you. For each of the spells make an estimate of the amount of "work" required to complete that task, convert to a convenient unit of measure. BTUs might be useful since that are already used to measure heat. For much of the time simply have the ambient temperature drop according to the amount of work. Picking a regular lock probably wouldn't be noticed. Casting a fireball would require a commensurate reduction in temperature in the ambient atmosphere and surrounding objects. Or, at least this could be a primary source. It would allow people to recognize and trace the use of magic simply by weird changes in ambient temperature.
And, naturally, larger spells might require a bit more work because they are drawing energy from a different source.
Earth magic may be cooling the Earths Core.
Lunar magic may be drawing energy from the Moon's momentum.
Solar magic may draw directly from the Sun.
and so on.
This could help differentiate between the power available. The scale of potential energy is quite different in the Earth, Moon and Sun. But there are other factors -- Immediacy for example.
Isaac Asimov had a short story where scientist in two parallel universes exchanged atoms resulting unlimited energy on both sides of the divide until one of the scientists realized that the nature of the system was imbalanced resulting destabilization on their side, but scientist 2 refused to shut the system down (or didn't have the authority) because it was so great for them... I mention this because perhaps your mages are pulling energy from a parallel universe. BUT in doing so destabilizing both universes. If energy is conserved how much extra energy can wizards add to our own universe before our universe is no longer stable?