Choose a creature within range. That creature must make a Charisma saving throw or become trapped in a harmless prism-shaped demiplane, which is twice the creature's size. A willing creature can choose to automatically fail the saving throw. The targeted creature can do anything it likes while in the demiplane, including moving and taking actions, but it can't willingly leave the demiplane by anything less than a Wish spell.

 Before the spell ends, as an action, you can cause a portal to that demiplane to open up at a point you can choose within range. Nothing from outside the demiplane can enter through this portal, and vice versa, except if it is part of a melee or ranged attack.

 The creature must attack a target that you choose within 5 feet of the portal. The creature chooses this attack. Then, the creature may repeat the saving throw. On a success, the spell ends, and anything in the demiplane is ejected out. On a failure, the portal then closes. you can take this action as much as you want until the spell ends.

 If the creature drops to 0 hit points, the portal reopens wherever it last opened (if it wasn't opened earlier, the portal opens where the creature used to be before the spell was cast) and the creature and everything else in the demiplane is ejected out (no saving throw required), ending the spell.