1.Find the first skull in the last room near Jugganog
2.find The seacond skull in the Graveyard
3.Find teh third skull near mule kick
4.Find the last skull at spawn near the door buy
5.Go to the church and do a small ritual
6. collect the key and open the door, revealing Pack-A-Punch

Note: the skulls have to be feed soals of the undead to proggress, and the end game door is in the same room, costing 50000
Hope i helped :p