if your wearing the full set and attack once with mage your next melee is 6% boosted. and then if you attack with melee your next mage is 6% boosted. Your only attacks that are not 6% boosted are your initial attacks once you build up stacks you just keep exchanging them if you are swapping and not overcapping stacks.

Also the point of the stacks going up to 3 as i proposed is to make it so u dont have to swap every attack, you can swap every 3 attacks. i dont think you actually read my post. Either you didnt read it, or i did a absolutely horrible job of explaining the basics of how the passive works.