A lil somethin somethin: You can find the details for this event on the announcement page here.
Hi, We have a fix for this coming at launch (we enabled Dynamic Culling for the skill so its performance should be better if you have the setting enabled).
For clarity, in our livestream we mentioned that Sacred Wisps would always trigger when a Rare/Unique enemy is nearby. To avoid performance issues, we've reduced their chance to trigger but have increased their damage to compensate.