@NatureMC @pho4cexa it's complicated! 
It tries to detect crawlers (and does a decent job of that), and if it detects one, serves it garbage. The garbage is whatever the admin configures. By default, it is random symbols from Rust code (iocaine's own source) - harmless, but also useless. Its possible to go much wilder, click around on https://poison.madhouse-project.org/ for samples :)
The garbage is full of links, sending the crawlers deeper into the maze.
It's not DDoS, because 1) it isnt distributed; 2) I am not sending anyone anything they didn't request. Iocaine responds. If any bot finds that overwhelming, they can stop crawling. I'm not sending large amounts of data, either: 4-10kb text, small images. No zipbombs, no gigantic files, no endlessly dripping content.
It is different from Nughtshade and Glaze, because it doesn't change your content to make it poisonous. It stops the crawlers from reaching them in the first place. It is both a tarpit, and a bot detector - but the deyection works well enough that the vaaaast majority of the bots can't get past.
It isn't 100% effective, but it reduces the problem considerably. It does have false positives, but few, and those are easier to make an exception for than catching the crawlers otherwise.
(More in the next toot)