If you want to get philosophical, then the law of energy conservation isn't true. It's only true enough to be useful. Or it's true enough on certain levels of analysis. Hopefully
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Quara guy knows more about physics than me. Another source has also mentioned to me that the statement "Energy can neither be created nor destroyed" has been dissproven by modern physics.
^^ But obviousely this doesn't matter. The recorded instances in which the law of energy conservation don't hold true couldn't explain anything close to what abilities are doing in my story. If you want to say that they are simply using the energy present in another universe, you can do that. It only pushes the problem back one step of analysis. Because then I would ask how are they doing this aand do they need some sort of enery to do that.
When creating magic systems I usually go with the explanation that there is a non interactive medium (non interactive so it's plausible that it hasn't been discovered) and then through some mechanism this non reactive thingy becomes reactive and does stuff. This much usually satifies my inner monk that screams THE GIRL WITH WINGS DOESN'T CONFORM WITH THE LAWS OF PHYSICS
Afterwards I go mental and let magic do any number of things, even those that would be hard or impossible to explain with the non reacive medium idea. But it doesn't matter since every time my inner monk scrams I can throw him the non reactive material (usually Aether or Mana) theory and he is busy trying to figure out if his complains still hold true in that theoretical reality.