Well I would say that the one that wins the initiative would win the fight. First strike can disrupt mage concentration and mage first spell can end the whole fight!
And donīt forget that at lvl 40 guys have so tupidily high saving throws that you have to cast spells with no saves alowed to get anything to happen..
And, a level 40 barbarian could still throw a mage of a cliff...
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Yawning lazywolf dreaming about nice little fairies...zzzzz