Bungie's way of showing you that Eris is that one person who has to ruin everything. Like that one house around your block that you know every year not to goto because of the little baggies of pennies & boxes of raisens, you get. Bungie also shows their sense of humor making Cayde-6 wear a Eris mask for the event. Also if you're not a year 1 player, the whole "falling" off the tower with the atheon mask is a direct nudge to the player base to cheesin him off the level.