Killing this creature will bring back the player that was banished.
This creature should be eliminated immediately. Not only will your team be down one valuable monk, but Shiro becomes extremely resilient while it's around.
Even though they are not marked with a special aura, the death of these creatures will give a Morale Boost and recharge all skills (including Resurrection Signets and Celestial skills) like the death of a boss. In addition, they do double damage.