Playing with my kids and we wasted over 5 hours doing this for the quest to not spawn skeletons near end.
I get bugs happen but this bug has been around for over 4 months and its also noted as a bug and still has not been fixed like really!!!!
Make it so we can reset the final fight.
I wont be going near this quest and sort of made us lose interest in the game now as its a game breaking bug and devs are just to slack to hot fix it.
I wouldnt really care if it took 20 mins to do but this quest takes many hours and to have it bug at final stage is a real kick in the guts.