Weird New Lag

For the past few weeks, I've noticed this lag that occurs when dueling. My spells highlight when I click them but they act as if I am disconnecting where I can highlight as many at once as I want, and it lasts for 3 or 4 seconds at a time.
This lag spike does not impact player movement or messaging. It only impacts my spell casting.
My ping never goes over 150ms, even during these spikes.
It seems like there is some new issue server-side that is inducing lag into a healthy network connection.

Doesn't happen to me