what the heck how did you get one at the end of the quest still? I beat the last boss yesterday and it said there were no more left 
I think if anyone is getting Wizpur from this mission, it’s from an egg. The developers confirmed a while ago that there aren’t any prizes left to get.
But do tell if it wasn’t from an egg, because that’s a serious bug in that case. (Just want clarification on that).
Once the quest is over is that monster gone for good or are they still obtainable some other way or from eggs?
I personally found that the monster in there did not yield particularly good experience relative to some of the other dungeons in the game (excluding the tower of course)
just one move attacks (all three monsters), then there’s one that boost attack for your team, one that summon a casual monster (killin the last monster of your party) and the last one prevents all damages from dark types (just for the meowzard though…) without any suicides or anythin.
@kookaset if only i could give one of those to you lol
I did beat the boss two days ago, what appears to be the same day you are quoting. I dont know if it’s becuase i got one while there were some left or as ashley mentions below it was a bug, but i did not receive the message you are quoing. My reward screen from beeting the final boss was both the rookie form of meowzard and a golden mission egg. If it was a bug Ashley will now be notified if it was not a bug then I guess I was one of the last few to obtain one of the thousand.
For fear of loosing my Meowzard but bettering events in the future,as i mention above I did receive a wizpur for beating the final boss two days ago. I was pretty surprised but then I had seen people posting after the fact that they were receiving the banner stating there were no more prizes left so i figured i was one of the last. Hope this helps, just to clarify my wizpur was non egg related but mission complete related.
I got a S Wizpur 5 days ago 
Its now a Lv.99 Meowzard 
Wasn’t able to get one and lost out or the destroyer even though I did it in the first couple of hours of the morning