What you were expecting to happen, and what actually happened?
When I first use the Eye of Xanethos, I expect it to deal 11 damage to my enemy, and 22 if the target is fey. What happens pretty often is that I deal double damage, whether the enemy is fey or not (or at least that is what I think happens, since I just kill off the enemy).
What are the steps to make it happen again?
Use the Eye on a non-fey enemy with over 11 life/armour. See it die anyway.
Do you have any screenshots or video you want to share with us so we can see the problem? Attach them to your post!
I need to start screenshotting everything then… sorry. This happens pretty often actually when I play the Arena. I’ll try and post a screenshot if it happens again.