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In Harry Potter, it is said that Lord Voldemort is one of the most powerful wizards of all time. But I am not very convinced about why that is the case. I guess, a more general question is, how can you tell if a wizard is powerful?
In terms of spells, to be specific, the death curse, if two wizards speak this curse to one another at the same time with the equally good wands, then who will die? Does the effect of the spell depend on the way a wizard speaks it? If so, it what way exactly? Can an average wizard cast death spell to Lord Voldemort and kill him?
In terms of wands which is sort of the guns of our world, how do we know if one wand is more powerful than the other. In the movies, I did not see why the elder wand was that special except that it looks better.