There is no bug. Every critical hit made by skill will recover a certain amount of energy. Every critical hit made by skill will provide 1 stacks of Nature's Point, so if you have 1 Nature's Point, you can still do 10x hits as long as every consecutive attack is critical.
This information were missing in skill tooltip, will be added with next patch.
Greetings
Thanks for the info, that's good to know. I rlly like that behavior and the mechanics. However, the same or an equal mechanic would be cool for Sandstorm in AoE dmg. At the moment it happens, that you loose all your NP with Sandstorm and can't use your Widow spamable effectively on single targets afterwards to finish surviving mobs. In our runs, the surviving mobs died too fast, not being able to hit with Earth Arrow.
Furthermore I don't think the class needs NP with dwarven Ale. Wach Druid have their own skill which reduce the NP cost of all skills to 0 . It is like a class specific dwarven ale.
The Druid/rogue cannot be a burst class, because you have not such selfbuffs like rogue or scout. But the sustained damage is strong
I don't say it needs to be a burst class, it's good how it is atm, but only use case for dwarven ale would be sustained trash dps, which is very bad compared to other classes due to sandstorm is using all your NP at once.