Prepare yourself for an battle with several monsters of 75, Don't take to much food with you, because you can only eat food at the first boss, take an spade with you to, and go into the stronghold again.You can use the portals to teleport to the center, if you already claimed the reward of that floor. If you didn't already claim the reward, you must go though the Stronghold, look out for the monsters! Also after you defeated one horsemen, you can better claim the rewards, so you don't need to travel though the dungeon once again.