Here is the full list of all 9 Magnibox achievements.
You have mastered the power of + metal.
You have mastered the power of - metal.
You have mastered the power of + boxes.
You have mastered the power of - boxes.
You have mastered the power of polarity.
You have mastered the power of clouds.
You have mastered the power of magnet clouds.
You have mastered Magnibox.
You found them.