It’s possible for players to either accidentally or on purpose stop the event from proceeding by killing the first wave of grawl that come to look at the snownorn army. If those are killed then they can’t go back, get the grawl shaman and keep the event going.
TL:DR
The grawl army needs to be made invulnerable. If they die the event stops proceeding and Rani stands there until server reset.