Mindblade Spectre

These Mindblade Spectres will interrupt your spells, even spells like Death's Charge that only have 1/4 second cast time.

You are still able to cast off of them following certain procedures due to the fact that they break at +33% Movement Speed. See Aggro for more details about breaking with movement speed.

Basically you want to gain distance between you and the Mindblades so you are out of spellcasting range. To do this, run forward with +33% Movement Speed to somewhat break their aggro and gain distance, and then also Heart of Shadow off of something to gain even more distance so you are out of their spellcasting range. Then immediately cast a spell such as Shadow Form. Be careful not to actually break their aggro if you need to keep their aggro. See https://youtu.be/HIKR2o4D8xU?t=791 for an example.