Spell duration does not seem to have any affect on DOTs (Shaman). I tested it with 0% and 24%. Both tick 6 times, and last for the same overall duration.
Is this a bug or by design.
Spell Duration on DOTs
Re: Spell Duration on DOTs
They never did, please investigate before posting here. If you ask "Is this a bug or by design." then you did not research your topic.