The Living Wall… one of those… weird monsters that D&D is sometimes famous for, this one appeared in the game through the Ravenloft campaign setting for 2nd ed. It’s a section of wall made up of the corpses of creatures (read adventurers) it has absorbed and taken up as part of its structure. Above all else Its ultimate desire is to kill the one that created it. Evil wizards usually create it to guard a location or object.
I was asked to try to make one for 5e, but when I read the 2e description I thought that it wouldn’t translate well (it has as many attacks as creatures absorbed, so it could attack like 15 times if it absorbed 15 fighters), so I changed some things for 5e and took some liberties. I also changed the alignment, it just didn’t really read as a Chaotic Evil creature to me.
So here’s my version of it. A Challenge 6 critter that tries to absorb you into its structure. It has various weapon attacks and can cast spells (to represent other adventurers it has absorbed). It has magic resistance, an illusory appearance, and if it absorbs a character, it gains its hit points.
Check it out, tell me what you think. Where would you put one of these in an adventure?
www. Newbie DM .com 
Q
April 21, 2015
I need to use this in my campaign, ASAP.
vishalicious
April 21, 2015
I got my start running games via the old 2nd edition Ravenloft. Its still one of my favorite settings. This was a great blast from the past. 😉
Fwinters
April 21, 2015
Ravenloft. Oh memories.
RPDM
April 26, 2015
Ravenloft. Oh, the nightmares. ^
Yeah, gotta find someplace to put this in an encounter. Maybe ramp up the horror of it by playing it as the Cenobite pillar relic from Hellraiser III: Hell on Earth.
newbiedm
April 26, 2015
I think you need to run a SFX like this: https://www.youtube.com/watch?v=Qt5FoYN31m0
to highlight the creep factor of all the thing trapped in it speaking at the same time…
David
May 7, 2015
I never found a good spot to use a living wall in an adventure during my 2e days. Conveniently I’ve got a good spot for one coming up in my 5e game in a week or two most likely. It’s even the right CR!
Samuel Levesque
June 23, 2015
Okay, I must make it official. Thank you! I have just used two Living Walls (both North and South walls of the same room), and it was lots and lots of fun. My group certainly felt the dread upon them, with all of its “unexpected” abilities (aka the Wall starting to blur, which freaked them out). And I got to pull out my old and rusty Vicious DM smile, that was liberating… Anyhow! I like having lots of different monsters, and this one definitely have its own spice to it. Woohoo!!!