So I was wondering if anyone has any ideas for rule Tyranid hybrids, Magus or even Patriarch

There's a broodlord over at Final Sanction, the free adventure for Deathwatch.

For hybrids, I'd just use standard profiles and generously season them with mutations.

On Dark Reign there is a genestealer cults supplement, written by yours truly, it should have the proper stats for them...
Do mind it was written before Inquisitors Handbooks came out...