This event needs to happen more often. I'm actually a bit lucky because I'm working towards Astralaria Collection IV, but I've been waiting with some really nice folks who are working on the new Zhaitan legendary skin collection and this event needs to fail in order to guarantee us both a drop for our collections. As it stands now, the event seems to happen every 1.5 - 2 hours, and since it's not on a timer, if you go anywhere else, you risk missing it. On top of that, convincing players that come along to let the event fail is like pulling teeth. It's impossible.
Like I said, I'm lucky since I can complete my collection on the defense event (ya know, on the off chance the Wizard feels like spawning), but those Zhaitan skin collectors NEED it to fail. I've done this event 3 times now and have yet to see the Risen High Wizard spawn which roughly translates to about 5 hours of game time literally just sitting there waiting for an event on a sporadic timer. It's just not fun for anyone. I want to go play this game and make more progress towards my first legendary! I can't do that when I'm sitting around waiting.
I don't know if changing the event timer to be shorter is the best way to fix this, but I think something needs done to address this.