I have quite a few favorites, but I had a really good experience this last event due to some character stuff that had happened beforehand.
To set up the story, I have to explain why my character has an intense fear of anything related to Blood-based magic.
A little over a year ago, I was Gypsy cursed by a player. The actual details of the curse are irrelevant, but what matters is the roleplay involved. See, I am not a tall person, about 5'8". The other player TOWERS over me, somewhere in the 6 foot range. Now, he and I are friends in-game, and at the beginning of the event, he asks me for a hug. I was cautious, but said sure...which is when he pulled his blood-drenched hands out from behind his back and GRABBED MY HEAD. He starts cursing me with his blood, and I'm screaming trying to get away, and we both fall while he finishes his curse. Everyone is yelling, people are about to start killing each other, it was a whole big mess, and for Taios (my character), this instilled a fear of blood-based magic that has only grown with time.
Fast-forward to this event. We were attempting to stop a spirit creature from manifesting on our plane and doing all sorts of bad stuff, and I agreed to go take care of a part of it without knowing what I had signed up for. We rift in to the area, and wouldn't you know it, it's the most horrifying thing that Taios could have to fight.
Blood Constructs.
I'm flipping out, but I push through it so that I can help my guild, right? Well, some of the constructs, it turns out, require a killing blow, or else they regenerate. I decide to do so myself, and that's when it happens. As I strike the blow, the construct explodes, covering me with blood and ichor.
I screamed. It was bad.
Not only that, now that I am covered in the blood, I CANNOT BE HEALED. Purify does nothing, no healing can get to me. And I was stuck with KB duty for the rest of the mod so that we didn't have too many people unable to be healed.
Luckily, when I died later that mod, I was able to take a hit to my max health as part of a deal with the powers running the constructs to become immune and to wash away the blood that was already on me, so that mitigated the damage to my character's Psyche. Still, being covered in magic Blood was the most scarring thing my character has ever had to go through, and I loved every second.