I really like the concept of defiant stacks. Especially in dungeons where 5 people are challenging a boss with 5 stacks. Its very satisfying when you are able to interrupt the bosses “big damage” attack because the stacks were managed effectively (reduced to zero ahead of time) leaving them open to a single interrupt at the opportune time.
I really hope to see that mechanic used more, and in some cases, enforced in a fight.
It would be very satisfying to have a boss that has a “raid wiper” ability that must be interrupted despite a 5 stack of defiant. It would require the team leverage their interrupts, communicate clearly, and work together to defeat it.
Interrupts create a level of depth that players can really enjoy. It requires knowledge about what attacks are coming, strategy about how to deal with those attacks, teamwork on how to manage the interrupts, and skill to pull it off. That group cooperation is a critical piece to what makes boss encounters fun for me.
To restate: I really like the defiant mechanic and hope to see it used as one, and not just a deterrent against ever using interrupts to begin with.