Today I finished the last few Blood and Madness living story achievements. When you complete the meta achievement, you get a mini candy corn elemental and unlock three additional achievements.
Before you head to the Haunted Nolani Waypoint in the Black Citadel to finish up your achievements, make sure you have at least five candy corn in your inventory. It is also recommended to be in a party with at least two other full damage buit members. Head to the star icon on the map and talk to Tessi to begin the fight. When the Bloody Prince appears and turns red, stand next to him and quickly eat five candy corn. This should cause you to become sick and puke on Thorn, giving you the Upset Stomach achievement.
Now, to defeat Thorn, you have to stand in the pink glaze puddles that Tessi shoots on to the floor. This will allow you to damage Thorn. If you are not standing on a glaze puddle, your attacks will do 0 damage to Thorn. Occasionally, Thorn will vanish and summon minions. Stand in the glaze puddles to do double damage to these minions and kill them to get Thorn to reappear. Defeating him in less than a minute gets you Beaten Bloody. Watch the cutscenes and complete the instance to get You, Back in the Box! and a candy corn node in your home instance. Your personal candy corn node seems to give double the amount of candy corn than a regular candy corn node and can be mined once a day all year.
With all the achievement points I got from this living story, I finally reached 7000 achievement points. I picked the Zenith Short Bow this time.