EoP PSA: Your specials will never crit Warlock unless his armor buff is gone
Addendum: when previewing content and reading the node descriptions, you can now also see the defender's abilities as well in the same screen. This is something players should get in the habit of doing, especially in content designed to be difficult or tricky. There are lots of abilities most players are unfamiliar with, even veteran experienced players. When you see something weird going on, reviewing what the champion actually does should be the first thing everyone checks. Doing so will prevent a lot of pain and frustration.