Corrupted Wood can be found mainly on the Corruption layer, which currently is the deepest layer of every Creativerse-world.
On many of the currently newest template Worlds RW 4-8 a few blocks of Corrupted Wood looking like trunks of thin trees are floating over the surface, like over Water or Grasslands; however they are rare findings.
Corrupted Wood can also be "created" by different means by players.
Since there are usually no caves leading from the surface as far down as the Corruption layer , you can only reach this layer by digging downwards (by using the according Power Cells needed for mining through each layer). The deeper you will dig, the harder the rocks will be that the layers are made of, and the harder the survival will be there.
- throwing Corrupt Bombs at Wood (to craft them you'll need Corrupted Stone, Corruption Dust and even some Lumite)
- touching Wood with either Corrupted Water, Corrupted Wood, Corrupted Dirt, Corrupted Grass, Corrupted Leaves and/or Corrupted Stone. You can build whole platforms from Wood with only one corrupted block in it, and in time the corruption will spread by itself over all the wood blocks that are touching each other
At least that's how it currently is as of R27 in January 2016, see Corruption (spreading).
If you corrupt Ashenwood, it will turn into "Corrupted Ashenwood" (looking exactly like common Corrupted Wood though) and Elderwood will turn into "Corrupted Elderwood" (also not looking any differently). All other kinds of Wood will turn into "ordinary"Corrupted Wood.
However all Wood-blocks except for Ashenwood and Elderwood will turn into Cragwood if purified again, no matter if they had been Parchwood, Autumnwood, Shorewood, Weepwood or Wildwood before they were being corrupted. You can purify Corrupted Wood like any other corrupted block by using Purification Bombs or Healing Beacons.
Corrupted Wood can be used as a Fuel for Forges; 2 blocks will be needed for each process (of melting or hardening), it burns very fast and such is nearly the best fuel in Creativerse. Also Corrupted Leaves (you'll need 4 blocks of those each though) are fuel of the same high quality.
Corrupted Wood grows in the shape of long branches and/or roots spreading all over the giant "ceiling" of the Corruption layer as well as all over the ground like a web of thin roots, even under Corrupted Water.
Corrupted Wood also often connects ground and ceiling all over the Corruption layer with 1-block-wide slightly stems; sometimes sprouting into small to medium sized trees with bright purple Corrupted Leaves (without any blossoms nor beehives within) - some of them hanging upside down. These Corrupted "trees" might originally have been Cragwood, because if purified they turn into Cragwood and Cragwood Leaves.
Corrupted Wood is flammable (as are Corrupted Leaves), but will not easily catch fire. You will either need a Fire Bomb or liquid Lava to make it burn, and the fire will not spread easily nor far to other blocks of Corrupted Wood (or Corrupted Leaves) from where it initially started. Fire can still spread "well" onto more flammable materials; like uncorrupted Wood, Leaves, Tallgrass and the like, also many building-blocks crafted from wood and/or leaves might catch fire easily.