As two actions, your mind splits into two independent parts. You have advantage on Will saving throws and your second mind has an action which it can use to take a purely mental action (such as identifying a plant, herb, concoction, or spell or casting a spell) in the same round you take your normal actions. It has a mana limit of 1 and the mana is removed from your mana.
You can expend 1 additional mana to so the second mind’s mana limit increases to 2.
You can expend 2 additional mana to so the second mind can use two actions.