The Treecapitator mod allows you to cut a whole tree down, if using an axe of any tier (including custom axes made via the Tinkers Construct mod). When any part of the trunk of a tree is broken, all logs above that block are broken, as well as any leaves next to the tree, dropping wood blocks, saplings, and apples. The durability of the axe used to cut the tree is decreased by the number of wood blocks cut down. It takes much longer to chop the bottom log of a tree with Treecapitator, as all of the upper logs are broken with it. A tree is defined as a vertical pillar of logs with at least 3 leaves blocks adjacent to the top.
Treecapacitor WILL work with giant trees in the Twilight Forest dimension. However, keep in mind that the durability lost may be greater than the durability of the axe when cutting down extremely large trees. If this happens, the largest amount of wood able to be chopped with that axe's durability will be cut, and the axe will be destroyed. To avoid lag spikes, it is recommended to use shift+click to chop trees down in the Twilight Forest.
Holding shift while chopping a tree will disable the Treecapitator mod, allowing you to break blocks as normal.