As two actions, your mind splits into two independent parts. Each part functions in complete autonomy, like two characters in one body. Your new “second mind” does not control your body physically but is free to use any action on your turn if the action is purely mental (such as casting a spell) in the same round you take your normal actions. It can cast spells and has a mana limit of 1. The mana is removed from your mana or psi.
Both your minds communicate with each other telepathically. You have advantage on Will saving throws.
You can expend 1 additional mana or psi to so the second mind’s mana limit increases to 2.