No pets.
Events just Christmas event w/ Halloween paint and a unique bossfight.
The stuff requires Halloween races, but those aren't implemented.
Artifact Costumes. Really............ Lemme guess there's a +21 gear floating somewhere in this update. Your artifact backs Rival EW 2-star wings.
New Medals. If you know what Socket Extraction Amount does and like having it, you're gonna love em.
Funny main boss. He just L0L's and does more joke attacks than anything.
Mission bosses are Elluman for F1 and Night Lord for F2.
F6 needs a Defense order which quite frankly is a once a day quest thing during event. No drops that I know of.
Halloween candy is decently low cooldown and not too bad hp for mid-levels.