Sometimes the link between two series can be of paramount importance to the story (such as Alpha's appearance in "Judge Dredd"); in other stories the reference can be a passing homage to an earlier tale with no effect whatsoever on the plot of the story in which it occurs (such as the reference to Satanus' ancestry in "The Cursed Earth"). In either case, once a connection between two series was established, it was often repeated. For example, "Top Dog" was followed up by "Judgement Day," and the reference to "Flesh" in "Judge Dredd" was reciprocated by the cameo appearance of a Mega-City judge in "Nemesis the Warlock Book V," which was itself a crossover with "Flesh" because it featured Satanus in a major role.