|Ben Iglauer RPG Superstar 2015 Top 8 , Dedicated Voter Season 7, Dedicated Voter Season 8 aka moon glum|
While this monster was not my favorite, I think that personal tastes aside it may be the best monster of the bunch. Its story matter is excellent in that I could use it to create a whole 1 session adventure based on the monster, and it is poetic, sorrowful, and horrific. I immediately reminded me of the Harlan Ellison short story, 'The Whimper of Whipped Dogs'.
Then the mechanics present unique abilities that could well lead to some memorable and terrible battles.
With regards to Alanya's comment above, I think that people can see them, but they will have 20% concealment and you will be flat footed without true seeing. That's the way I read the naturally ignored power.
I also read the isolate power as allowing someone to attack a tatterghoul that is fighting an ally, but the they can't target the isolated ally with anything helpful (e.g. mass cure wounds, bardic performance, haste, aid another action), though the power is unclear on this issue.