Same as most people lil more loot and double xp. My personal idea would be, to not make a santa boss, but instead the wraith to something santa related, using a giant candy stick as weapon (and a christmas hat). Not that stupid...scythe giving someone randomly an item, or killing everyone as usual (saying the phrase you werent a nice boy! would be epic but not doable probably) (this personal hate against the wraith is not because of him ruining my runs in the last time pretty often *cough* and is not to be taken serious as idea ^-^) 