In regards to plumes you should typically expect them after stomps. I see nothing wrong with pattern-based fights since you can always anticipate the next set of moves quite easily and has been in video games since forever anyway.
When it comes down to it, all the fights in an MMO are pattern-based but when one of your mechanics comes down to you needing to be dodging it before it even starts to happen, I feel like you've designed wrong. In an action RPG or hack/slash, sure thats the making of an epic boss fight, in an MMO, not so much.