I always use Mangrove Jack's lager yeasts, mostly M84 Bohemian Lager for bock. However, I only brew bock once, around December/January, so that I can ferment at lager temperatures. I ferment for one week, then rack into a secondary vessel, one week around 16° C, and then I put it in my garage for a couple of weeks in the winter so that it becomes clear. Then I bottle with a little bit of bottle yeast.