My primary world, home of the original Glass Island and Skyrail system.
My modded world, featuring the delightful 
Super Hostile - 
It may not be a large tree by Carnage standards, but a Shadowheart is certainly imposing. Twisted helix branches curve up towards the sky like claws, with little foliage and the odd iron deposits. Lower down on the trunk blocks of obsidian adorn it.
My glass skywalk abuts directly onto the Shadowheart's lower platform, and I waste no time in bedecking it with a plentiful stockpile of cheery torches. Night is falling by the time I've lit the lower area to my satisfaction, and I can hear the rattle of skeletons below, along with the occasional zombie groan.
I've run out of torches, but off in the distance I can see something glowing - glowstone, to be precise, and what looks like some kind of construction or road leading to the water. There's no time to look, it'll have to wait for morning - I flee back to my shelf pine bolthole before anything scary comes calling.
My safe home turns out to be not so safe, for there's a two block high hole in my wall... that I don't remember putting in. Some glass blocks seal the breach for now, but they don't explain how it got there in the first place.... with trepidation I explore the rest of my tree, but nothing scary seems to have taken up residence in my absence.
The next morning, and I'm already hard at work mining the easily reached surface iron ore on the Shadowheart. A few blocks are sadly lost overboard, but most of them are ending up in my pack, so there's little motivation to face the potential dangers of the forest floor for so little gain.
I've got a nice little stockpile of iron bars accumulating, but I'm not sure what to make of them. The second chest nearby had yielded a nice set of iron armor already, and armor in general was not actually of much use to me. I fall off things far too often, alas. I've chopped and mined two of the upper branches so far, whittling down the Shadowheart from the top block by block. Thus far, it hasn't proved to be nearly as sinister as its name implies... that is, until I find this.
The Shadowheart does indeed have a dark core, one, possibly more spawners. I wasn't inclined to poke about but quickly sealed up the hole. My sneaking suspicion would be these are skeleton spawners. How to deal with this will require some thought.
