Werebear Form is still the Druid mastery skill and is therefore Druid exclusive. The other skills exclusive to Druid are Swarmblade Form and Entangling Roots. The non-exclusive Druid skills are Spriggan Form and Summon Spriggan.
This is not always the case. There are a lot of different factors that go into the decision making of whether a skill is exclusive to a mastery class or not. For example, werebear form would be a useful skill for melee beastmaster builds, but it’s druid specific in part to make melee druid builds more distinct from melee beastmaster builds.
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