You turn up to three normal-sized centipedes, spiders, or scorpions into larger forms. Only one type of vermin can be transmuted (so a single casting cannot affect both a centipede and a spider), and all must be transformed into the same giant forms. Your level determines the largest giant forms available to you; see the table. (You can always choose to turn the vermin into smaller forms than the largest available one, if you wish.)

Any giant vermin created by this spell do not attempt to harm you, but your control of such creatures is limited to simple commands (“Attack,” “Defend,” “Stop,” and so forth). Orders to attack a certain creature when it appears or guard against a particular occurrence are too complex for the vermin to understand. Unless commanded to do otherwise, the giant vermin attack whoever or whatever is near them.