I don't know the exact details but it's not officially created by Toro and did start as a joke.Didn't Toro end up deciding to create it for real after such positive reception for the original April Fool's joke?
You don't need to restart, just skip the boss room and get more souls to buy outer one souls from mabel. You only need 1 more soul to be able to break old king. If you need to leave the dungeon, that works too. You can start in the depth/layer where you left off but you won't be in the boss room.I'll try restarting the dungeon, i'm at 2995 luck and i tried breaking 5 times in a row and none hit
You could equip something to put you over the luck threshold. Turtle soup ladle gives up to 50% luck boost and stat boosts work too (omnibless).
 
				
		 
			 
 
 
		 
 
		