Terraformer flattificator, as my experience (several weeks of intense use of terraforming...) works:
- It remove blocks above the terraformer, up to 20 (Y+20), but only removes dirt, stone and may be gravel.
- It create dirt at the same level and below the terraformer, i suppose another 20 blocks, but i dont sure... only create dirt in empty spaces, and always need a block to suport, do not create floating dirt.
- Horizontally, it seems to have a range of 50 block radius, about a space of 100x100, but it is chunk dependant, i guess...
- It choose a higher point, and try to descend in the same column breaking blocks. If it find a block that is not dirt, stone, and may be gravel, it stop in this line in try another one at random. So, dont break any ore, but it need much manual help. It is incredible effective to reveal large large amounts of ores. So, you manualy need to clear torchs, cobblerstone, abandoned shaft stuff, or something like that to help it terraforming.
- It seem more effective horizontally near the terraformer, and work less in distance.
Hope it helps.