Cleon
Legend
I'm OK with incorporeal and CR6.
Sure...but what?
How about a Spot or Sense Motive check to detect when one's merged with a host?
e.g.:
Merge with Host (Su): Once per round, a death shade can merge with a corporeal creature. If the creature succeeds on a DC 20 Will save, the death shade is expelled and cannot attempt to merge with that creature for 24 hours. Protection from evil, magic circle versus evil, and similar magic prevent the death shade from merging with a protected host. On a failed save, the creature becomes the death shade's host and may be victimized by the death shade's control rage ability. The save DC is Charisma-based.
The death shade appears as a near-invisible gray mist which centers on the host's eyes, other creatures can detect the death shade's presence in a host with a DC40? Spot or Sense Motive check, the check is DC20? if the observer can see invisible. A death shade's host has a moderate evil aura when examined with the detect evil spell. A death shade can be expelled by the host's death or by successful use of a dispel evil, dismissal, or banishment spell against the death shade.
