If in real life, you put a tank pilot against a jet pilot, both of equal skill, you can be sure the jet pilot will have an advantage. It's the work of countering. If every blood counters the other, what's the fun of it? Your character would never be afraid of any other blood and the magical battlefield would be stagnant.
It's obvious that master mages would be, well... Lethal, but keep in mind that very few people actually reach that level of power, and the ones that do, are often too aware of the destructive potential they possess, to the point of refusing to use their powers to their full extent most of the time.
Besides, masters know their weaknesses. A pyromancer would know fighting an aeromancer is pretty much certain death to them, as would a hydromancer know that an electromancer is very dangerous to them, due to the conductivity of water.
Psychomancy can disable most, if given time. But their actions require such a level of focus that even a single distraction can disable their offensive capabilities for the time required to kill them. Freeshooter, you're putting psychomancy on a pedestal. They truly aren't that special. You think they're OP, but in reality, just flick their nose or send one mentally trained pyromancer aided by a rune at them, and they're done for.