I haven’t used necromunda since the first edition with the sustain fire dice. I had a delaque gang and a genestealer gang (from I think citadel journal).
the gang had the chance to purchase a genestealer (took a massive amount of credits) and when emembers gained experience there was a chance they would retire to breed and you got a new hybrid.
are there any rules for genestealer gangs for necromunda and if so do they have the option to take a four armed blender machine?
1) Yes, there are rules for Genestealer Cults in the current edition of Necromunda. GW released a pdf of rules for them a few years ago that you can find here, and they got updated rules in the Book of Ruin supplement, as well as rules for the Genestealer tainted House Gangs (Including gangs becoming tainted mid-campaign!). Goonhammer has a decent review of their capabilities here
2) Purestrains are available, but only through the favors table (An optional rule in campaigns, with access to it controlled by the arbitrator), and then only if you roll a 13+ on a 2d6 (With +1 with each person with a higher gang rating in the campaign, capped at +3), and it will only stick around for one game. (The Favors table would be in the Book of Ruin, not the pdf I linked to).
However, Abberants are 3-armed blender machines, and you can have them make up almost half of your gang if you so desire!
Edited by Squark, 03 March 2021 - 04:33 PM.