From Wiki of Worlds Unknown
You can spread the effects of your spell to multiple allies by dividing its duration amongst them.
- When casting a spell with a duration of 1 minute per level or greater, you may divide the duration in intervals among the creatures touched. For spells whose duration is based upon your level, the interval is equal to the part before the per level text (i.e. 1 minute/level becomes 1 minute intervals). Spells with a fixed duration are divided into the next smaller interval (e.g. 24 hours => 1-hour, 1 hour => 10 minutes, 10 minutes => 1 minute, 1 minute => 1 round).
- School: Abjuration, Conjuration, Divination, Illusion, or Transmutation only
- Range: touch, 0-ft, or close
- Target or Effect: one creature or object, may not create an area-based effect
- Save: none or harmless
A communal spell uses up a spell slot one level higher than the spell's actual level.