In Battle for Azeroth, Focus is still a resource across the whole Hunter class, but it works a little differently for each specialization. Beast Mastery is staying the same (mostly passive regeneration), while Marksmanship is going back to a pre-Legion type of Hunter where the majority of Focus regeneration is active rather than passive. Survival is somewhere in the middle.
Today, in Legion, all specs have a baseline 10 focus-per-second regeneration rate (increased by Haste) and that makes up the majority of your of Focus. Beast Mastery supplements this with Dire Beast, Marksmanship supplements it with Arcane and Multi-Shot, and Survival is purely passive (but since Mongoose Bite costs no Focus, it sort of evens out).
And here’s how it looks in Battle for Azeroth:
|Focus in Battle for Azeroth|
|Focus Pool||Focus per sec||Generators|
|Beast Mastery||120||10||Dire Frenzy|
Beast Mastery is basically how it was in Legion — same passive regeneration, with only a small amount of your total focus coming from Dire Frenzy. Survival halves the passive regeneration, but can generate more Focus actively with its own version of Kill Command. This Kill Command has half the cooldown of Dire Frenzy and also has a chance to reset itself, which makes up for the lower passive regeneration. Marksmanship relies on casting shots to generate almost all of its Focus, so it’s basically the polar opposite of BM in the passive/active Focus split.
To visualize the difference in passive regeneration, here’s how fast each spec’s Focus bar fills up. This is taken while casting nothing, so the generators are not factored in.
So all 3 specs definitely have a different feel. I have to say that personally I prefer having more active control over my Focus. Marksmanship has zero downtime because of it, and Survival has a little. BM still has a large amount of downtime, but that can be reduced some with certain talents. I’m hoping that Blizzard can adjust some abilities and talents for BM to make it less of an extreme in this department (or at least give options for that).