Rendlerum

Rats don't generate pass tokens.  "Mindless: When this model is Summoned, it is treated as having already Activated this Turn, and neither player gains or discards any Pass Tokens."

Stalker, before 1.23, technically didn't gain any benifit from his threaten action, so it really was only a supporting action for the crew he was in, which was not really a stalker esk thing.  Now he actually gains something from it.

A pic of the void hunter can be found on p.349 of the TTB core rule book.  It kind of looks like longer, possibly four legged, version of a void wretch.