环绕苍蝇（Ring Fly）是重生中加入的一个怪物。Ring Flies are a new addition to Rebirth. They are pink flies that, upon entering the room, will cluster together into a circular formation and orbit rapidly while moving towards Isaac. They will hold formation even when you destroy all but one fly. The maximum amount of flies per formation is 10. These flies are fast and take up a large amount of space, so it may be recommended to hold these on higher danger priority.
- Ring Flies are not affected by 奇异吸子and will continue to stay within their current circular formation.