Issue 12: Midnight Hour is the latest free expansion to the game. It was announced on March 12th, 2008.
Issue 12 Open Beta was opened to all players on the Training Room server on May 6th, 2008. It was released to the live servers on May 20th, 2008.
The Midnight Squad
Join the Midnight Squad (Levels 10-20)
The clandestine organization of mystics, scholars and mages, known only as the Midnight Squad, seeks to rebuild its numbers since the devastating assault of the Rikti Invasion. The Midnighters hold a secret that could bring the alien assault to an end, but without the help of the Heroes of Paragon City™ it will remain Lost forever.
New Roman-Style Zone Maps (Levels 35-50)
The Midnighters hold many secrets within their walls, including a highly coveted Ouroboros crystal, enabling them to travel to the far reaches of time. There is a familiar threat in an ancient land and the Midnighters need the help of both Heroes and Villains to stop it. Players step foot upon the ancient land of the Roman Cimeroran Peninsula, where they battle deadly creatures, defend an ancient city and ultimately come face to face with the enemy of time itself. Throughout this journey players uncover the mysteries of power and the origins that guide them today.
Unlock Roman-Style Armor Costumes
Through their accomplishments, players unlock the new Roman themed armor costume set.
Villain Epic Archetypes
Infiltrate the Arachnos organization from within! Upon reaching level 50, Villains unlock two new Epic Archetypes; Arachnos Soldier and Arachnos Widow. They have their own unique storyline and missions, power combinations and costume sets. Branching powersets allow the Arachnos Soldier to specialize as either a Bane Spider or Crab Spider and the Arachnos Widow chooses from the Fortunata and Night Widow branches. Each brings with it unique costumes for your Arachnos duties, as well as your newfound role as a Destined One.
Using his newly built Resonance Manipulator, the Villain scientist known as Dr. Brainstorm™ has discovered a way to alter the energy strands which connect every Hero and Villain to their powers. This discovery has not only opened the door to new powers for his fellow Villains in the Rogue Isles™, but has also done the same for the Heroes of Paragon City ™! Specifically, new characters of almost every Hero and Villain archetype gain access to an additional primary and secondary powerset that they didn’t have access to previously. Details to come!
All have been verified here 
Hollows Zone "Gameplay Makeover"
Significant changes have been made to the Hollows zone to make it more fun! NPC encounters have been rebalanced, including new spawns, new villain groups, mission door improvements, and a mobile hospital has been added to the entrance of the zone. Additionally, Meg Mason, a new contact, has been added to give out repeatable missions.
Additional Character Slots
Issue 12 will add significantly to the number of slots that an account may have on each server.
The details of the increased slots are:
- Maximum of 36 slots per server.
- Two free slots will be given out to each account with issue 12.
- Additional free slots will be awarded through Veteran Rewards. These slots will be linked to every full year of veteran reward, and will be rewarded retroactively for all existing accounts with at least a full year of reward time.
- Purchase one slot for assignment to any server: $5.99 / €4.99 / £?
- Purchase two slots for assignment to any server: $9.99 / €8.99 / £?
- Purchase five slots for assignment to any server: $19.99 / €17.99 / £?
Major Gameplay Improvements
- Eight configurable new power trays let players customize their User Interface by placing them anywhere on the screen.
- Contact display redesign: Contacts are now listed separately as Active and Inactive, and players can sort contacts by a range of criteria including Name, Zone, and Level Range.
- Inspiration Conversion: Right click an inspiration to convert three of that kind into any one inspiration of another kind.
- Level Up Boost: Upon reaching enough XP to level up (at all levels), one of each type of large inspiration is immediately cast upon your character, and health and endurance bars are immediately filled.
- Chat improvements: Right click on character names in chat window to ignore, add to friends list, invite to team, etc. Drag any item (enhancement, inspiration, salvage, etc.) into the chat window so that you and others can click a hotlink to view the complete info box.
- More Real Numbers: Players can now display stats on powers before they choose them enabling more informed power selection and new temporary powers allow players to display enemy stats.
- Premade costume sets consisting of linked costume parts in the costume creator. 
- Saved character settings: Players will be able to save and load character settings. (Positron announced that they are "trying very hard" to get this feature included in Issue 12, but that it might not make it in.) 
- The ability to drag and drop character in log-in character list to reorder the lists as needed.
Other Confirmed Content
- Positron: In Issue 12 we are going to have you never dropping below 50% Inf. earn rate when in Supergroup mode.
- A new enemy faction in Issue 12 is pretty much defined by having a shield.  (This enemy group ended up being the Cimeroran Traitors)
- BackAlleyBrawler: More weapon customization options (including additional Talsorian options)
- BackAlleyBrawler: "Posi said he added the tokens for the rest of the Talsorian and Rularuu weapons today, so they should be in for Issue 12" 
- Confirmed Bugfixes: