The dragon spawns as it should, complete with a boss bar (not shown), and the bedrock portal to leave the end. (Complimentary Shaders + Better End Sky)
If the world is not specified in "config.yml", or the plugin did not edit the "level.dat" file of the world, the dragon and the bedrock portal both spawn as normal (Complimentary Shaders + Better End Sky).
After the plugin successfully edits the "level.dat" file of the world that's being dragon cancelled, the dragon and the bedrock portal will not spawn (Complimentary Shaders + Better End Sky).
"/dc check <world>" will check if a world is being dragon cancelled. Notice that it works on worlds created by other plugins (ONLY if they exist), this is because Dragon Cancel loads before the worlds do.
An End Crystal atop an obsidian tower in The End (Complimentary Shaders + Better End Sky).