Is there a deb based derivative of slack?
Um . . . . . No.
Slackware is kind of . . . manual. In fact, the only distro I can think of that is more manual is Gentoo. Even Gentoo is capable of resolving dependencies automatically, though, which Slack is not. This is actually why Slack is such a good distro for learning the guts -- if you have an unresolved dependency, it is up to you to figure out how to resolve it.
I used to run my systems as a very bare-bones Slack (or Slamd64 before Slack finally went to 64-bit) and then install whatever else I wanted from source. It was loads of fun to tinker on because it never tried to second-guess you. Good times!