Mystery gates are a new addition to Disgaea 2's Item World and onwards. These gates will spawn after three floors have been cleared or skipped. When the player enters the gate, one of many things will happen:
Disgaea 2 Mystery RoomsEdit
Orc Pirates: Get random pirate information and item chests which contain rare items.
Heavy Knight: A lone Knight that always has two legendary Chests and gives a tip to the player about the Land of Carnage
Dragon: Fight a dragon named Juzeppe. Has 1 to 3 chests available. Be careful not to hit the level 1000 Room exit NPC, otherwise it'll attack(great for really high levels though)
Chests: Free chests for the taking. Usually 3 with one legendary surrounded by two rare chests.
Item Shop: A Marionette named Cage runs the Rosenqueen Item World Branch.
Cellphone Shop: A Prinny named Yusack offers Cellphones for purchase. Talking to him too much will annoy him into attacking you.
Mana store: A Blue Skull named Muishkin sells mana potions.
Rosenqueen Dojo: A Sinner Named Selgio sells Weapon Scrolls.
Bribery Specialists: A Zombie named Samed lets you buy items for bribing Senators.
Hospital: An Alraune named Momolin who will heal the party just like she does on an Innocent Town
Rip off Bar: A room managed by Bolianne, a Succubus and 3 other female monsters. An Elbacky, Succubus, & Alraune with randomly generated names. Your Bonus Gauge will be increased at random just like the Bill in the Dark Court but at the cost of halving every unit's life in the base panel including Adell or by paying 10000 Hell. They will also attack if you talk to them with Bolianne saying, "We don't like the persistent type like you. I'll have to teach you a lesson with the rough treatment" before the fight.
Department Store: An Archer named Lime and the Item, Bribery, Mana and Cellphone Shops mentioned above. Each shop can only be entered once per visit. Talk to the store owner (or the Archer) too many times, and they will attack.
Ambush Room:7 monsters where one is the leader of the pack alone and the other 6 are set in teams of two. Complete in two turns to gain 3 levels on the item. (Monsters include any class including prinnies but on that specific floor they do not explode when thrown.)
Fortune Teller: Get a fortune from a Geomancer named Zhuar. Be careful, as it can be either a gain or loss of levels. (-10, -3, 3, or 10 levels). He can fight you if you talk too much to him and say; "Your new fortune is Divine Punishment" before the fight.
Lost Resident: You'll find a Collector, a unique resident that will want to move into your item.
The area doesn't yet count as a map, so the player can access the warehouse and items while in the room. To leave, talk to the Gatekeeper Ghost. Also when entering the monster room there is no Dimensional Guide meaning you must fight the monsters in order to advance since a Mr. Gency Exit cannot be used in a Mystery Room nor at the Innocent Town.
Unique to Dark Hero DaysEdit
Mao's Laboratory: Where monsters can be upgraded from Magichange 1 to Magichange 2
Paint Shop: A Holy Dragon will offer one free color change for any non-unique character in your party. After the first encounter, she can appear in the base town for a rather expensive re-paint job after passing a bill in the Dark Assembly.
Music Store: The Music shop NPC from the hub will let you purchase/change Item world tunes. This makes it more challenging from Afternoon of Darkness to obtain music, where the NPC was always selling music in the hub. Prices for music are also a lot more varied in price, from 100k HL up to 1,000,000,000 HL.with 100k, 500k and other prices being offered. This is also where you purchase music from DLC characters as well.
Fortune Teller: In DHD, the -10 result has been removed, and defeating him gives an additional +3 bonus levels.
Disgaea 3 Mystery RoomsEdit
Disgaea 3, in addition to several of the above events, has a few new rooms of its own.
Scalper: Sells Ilegal Tickets for unlocking the X-Dimension Maps. There are two Scalpers, one on Floors 1-49, and one on Floors 51-99. The Ilegal Tickets are very expensive, some costing over 10 billion HL so it is recommended that the player save up for them first.
Sphere Collecter: Gives out free rewards depending on the amount of Level Spheres collected. They range from Legendary Emblems to Special Items with Special Innocents.
Treasure Room: A room filled with many Treasures located on top of platforms with varying heights.
Treasure Tower: A room with some treasures and a very high tower with a Lord Cat God at the top that sells Serums. Talking to him the first time will award the player with the "Obey the Cat God" trophy.
Trophy Shop: A room with a single thief that gives the player the "Trophy Shop Trophy".
EXP Potion Shop: A room taking the appearance of an Ep. 7 Map with a Prinny at the end that sells EXP Potions.
Axel's Room: A room with Axel alone in it. Talking to him will award the player with the "Axel's Rose" trophy.
Gold Knuckle's Room: A shop with Gold Knuckle selling healing items in it.
Disgaea 4 Mystery RoomsEdit
In Disgaea 4, most of the rooms from Disgaea 2 and 3 are retained and includes more new rooms.
Evilection Voting Center: An Evilection Voting Center with various people waiting in line to vote. Talking to two NPCs writing out their ballot too many times will initiate a battle.
Conference Room: A Conference Room with a Wood Golem inside. If signed into the Playstation Network, characters from other players' games will be attending as well.Talking to him too many times will also intiate a battle. (Characters will also enter said battle as enemies)
Shroom Farm: A shroom farm with a Giant Eryngi as its leader. It contains various mushrooms causing effects such as Poison, Deprave and Level Up Meats.
Raffle Vendor: A vendor that sells raffle tickets which can be used to unveil Treasure Locations at different maps. The tickets are extremely expensive, costing 10 billion HL each.
Cementary Room: A room with a single Ghost acting as a cementary keeper. Talking to him will start a battle. There are multiple graves that will spawn ghosts if destroyed.
Prinny King: A room with a Prinny King standing on top of a Wooden Box Pile. Asks for 50, 000 HL to bribe the Gatekeeper with. If he receives the money, the next five floors you enter will have no Gatekeepers blocking Dimensional Gates.
Combat Training: Rooms spawns only if signed into the Playstation Network. Three level 800 Giant monsters can be fought if the Combat Chief is talked to twice. Characters from other players games join as NPCs in the battle, but are usually too low-levelled to be of assistance.
Save Icon Shop: An Android sells Save Icons to use as avatars for your saved game data. Avatars of any DLC the player has bought will be added to the shop's inventory. Talking to her six times will force you into battle.
Item Worlder Encounter: The Item Worlder from the Base Map will give you a free Mr. Gency Exit. Talking to her three times will force a battle.
Disgaea D2 Mystery IslandsEdit
Disgaea D2 changes how Mystery Rooms appear and is now referred to as "Mystery Islands". Unlike previous games, Mystery Gates do not spawn on an Item World stage. Instead, there is chance that the player will automatically enter a Mystery Island whenever a stage is skipped or cleared. A maximum of 2 Mystery Islands can appear in every 10 floors.
List of Mystery Islands/Rooms introduced in Disgaea D2: A Brighter Darkness:
Rock-Paper-Scissors Master: A Female Brawler who challenges the player to a game of Rock-Paper-Scissors. If the player wins, he or she can get a level boost to the item or an item such as a sardine.
Transfer Shop: An island with a Succubus who asks the player if he or she wants to skip a certain amount of floors. The player can skip 5 or 10 floors, but he or she has to pay to skip floors.
Innocent Shop: An island where a Thief sells rare Innocents such as Guardians. The player can only purchase one Innocent from the shop per visit.
Innocent Plaza: An island where the player can interact with the Innocents inside the Item. Talking to the Innocent increases its value greatly.
Item Boss Island: An island where an Item General/King/God gives a free 5%/10%/20% boost to the base stats of the player's item.
Character Counseling: A random party member will appear, talking to them gives three options. Choosing the right one will boost relationship with that character.