Transdementional rift

Rip open a portal into alternate world being the same as or being different from yours, it will always open to the location you opened it in in another world, you will always find yourself if your in a combat situation. The spell opens a portal 1ft away from you that last 12 seconds. you can jump through the portal, bring something through (ex. yourself) , or throw something through it  (ex. a goblin) if a creature is thrown through the portal and bumps into itself they merge into one and are dealt 1d10 bludgeoning damage. if you bring yourself through you both do the same action in one turn and you roll your damage dice twice as many times as you normally would. whatever you bring through stays for 3 minutes. you are not affected by bumping into your own self from another world. if you bring in more than one version of yourself you roll your hit die as many times as there are versions of you.  if the spell is casted in a 9th level spell slot you can choose where the portal in the other world will end up in the other world outside of combat.