A single boss standing on one tile asked everybody to be awake at the same moment, and most of the realm never was. What replaced it asks nothing of the clock: the Realm Boss stands for two days, anyone may strike it three times a day, and every fair blow counts toward a reward scaled to your own level. See The Realm Boss.

The two achievements that belonged to the World Boss were not taken away: they were pointed at the Realm Boss instead, so the players holding them keep them and they can be earned again.