Congrats on the coffin piece! Was it perhaps the piece that I'm missing the item ID from?
Here's a full list of all the special items available:
A Creeping Vine
Message in a Bottle
Recipe
Scroll of Alacrity
0.5 Scroll of Transcendence
(only on Felucca for maps higher than Level 1)
Skeleton Key
Tasty Treat
Treasure Map (Same level or one level higher)
For Level 5 to 7:
Forged Pardon
Mana Phasing Orb
Runed Sash of Warding
Surge Shield
1 Minor Artifact (only Level 6 and 7)
1 Master Skeleton Key (only Level 7)
1 Coffin Piece (only Level 7)
Some of these I forgot to add the item IDs in the original post... work in progress, I say!
I'd compare the Renegade Changeling to a paragon Irk. I never ever ever ask for help on a map... but I had to ask for help to get these guys down. They retarget, hit like a truck against all 70s resists, and are unbardable. You CAN provoke the other spawn onto them, but they tear it up quickly and the barding difficulty felt like 160. You can't lure them off, if they get to a certain distance away they'll reset back to the chest. I ended up having to switch to my tamer and call in another guild mate on his tamer. We invised and let the dragons whittle them down.
I haven't done a level 7 other then the first one in Illishnar, because I didn't upgrade my account to High Seas until recently. Before then I just sold the maps, since you can't decode them without the booster pack. As a general rule I find Malas, Tokuno, Illish, and Ter Mur level 6s to be way easier to solo, so when I get Tram or Fel maps I trade them for maps from those facets. I can't handle the ancient wyrms from the Tram/Fel maps on my bard.