Cage impalement

Roll 15 to activate the spell, The caster chooses a single creature within a  25 foot radius to be incased in a circular cage with magical spears around it that's a tad bigger than the person it was cast on, ( 1 ft taller and wider than the character.) Any other creature thats also within range of the creature the spell was cast on is knocked back five feet. The creature must roll a strength check of 15 or more to break out. If the creature does not break out in 3 turns, the magical spears attack and the creature takes 8d4 dmg, the cage disperses when broken out of or after the attack.

NOTE:The creature the spell was cast on cannot use any other action besides a strength check while the cage surrounds them