There is a very long delay after Mirror Images spawned from Teleport begin taunting and attacking enemies (they will stand perfectly still for a few seconds generally). This is annoying in general, but can be lethal in HC.
In addition to this I feel like perhaps range might be worth looking at as well? I’ve noticed there may be some inconsistencies in their attack/taunt range. I have nothing to back it up but I swear that sometimes they aren’t attacking when they should be (seemingly in range & have been summoned for a few seconds).