The Repressor is an Infantry Fighting Vehicle employed by the Imperium of Man, especially the Sisters of Battle and the Adeptus Arbites. Like most vehicles fielded by the Adepta Sororitas, it is based on the Rhino chassis with some extra armor on the sides, a taller crew compartment with firing slits and a small turret for its Storm Bolter.
It was created as a super-crowd-control vehicle for the Adeptus Arbites -- the dozer blade is for clearing mobs and barricades, the built-in Storm Bolter turret can be loaded with stun or gas grenades (or plain old bolter shells, for when they need to put down heretics), and the crew compartment is extended to contain six firing slits, so they can shoot from relative safety.
One day, a massive riot proved too much for the Arbites, and they called on some nearby Sisters of Battle to help them. The Sisters fell in love with the Repressor (after adding a Heavy Flamer, because no self-respecting Sororitas would go into battle without at least one fire weapon), and after they convinced the other Orders that, yes, it really was holy, it has been a part of their armory ever since.
The Repressor model was produced by Forge World, one of their few gifts to the under-appreciated Sisters. Unfortunately, they stopped producing them without explanation, so if you want one, you'll have to kitbash it into existence or pay the scalpers on eBay. That being said, you can get the pre-8th edition rules for free from Forge Worlds website here or from Imperial Armour Volume Two - Second Edition, so if you have a spare rhino and your friends don't mind a bit of proxying, you can still bring it to games.
On The Tabletop (8th Edition)
With 8th edition updates, the Repressor has arguably become one of the best transports in the game, mostly thanks to the rarity of fire points in this edition. For 5 points more than an Immolator, you get a powerful frontline tank which can transport 10 infantry models (except for Seraphim) and comes with a dozer ram, tripling its Attacks after a successful charge. The best part of the Repressor, however, are its six fire points. These let you do some really badass stuff, like running a squad of melta-Dominions 36" down the field and blasting the enemy at point-blank range on turn one, or carrying a fully-loaded Retributor Squad around the table, effectively turning it into a pocket-battleship. It's quite satisfying.
All this being said, the Repressor does largely suffer from the same problems it had last edition. Unless its carrying a squad around, it isn't particularly impressive, and its short-ranged loadout means it has to get really close before it can do anything. Additionally, its lack of access to melta weaponry means that, on its own, its only good against infantry, whereas the Immolator has both better range and more versatility in its weapons loadout.
On The Tabletop (7th Edition)
The Repressor fulfilled the role of frontline tank for the Sisters of Battle. For just 15 points more than an Immolator, you got a tank with more front armor, a storm bolter, a dozer blade, more transport capacity, and more fire points. It also came with a heavy flamer, making it an excellent choice for Dominions or Battle Sisters. It was especially valuable to Dominions, since the fire points on the sides and top allowed the entire squad to broadside enemy models while retaining mobility and operating from a position of relative safety. It's thick front armor, combined with Shield of Faith, could make this thing a real bitch to take down.
Unfortunately, it did have some drawbacks compared to the Immolator. For starters, you couldn't change it's weapon loadout, meaning that you were stuck with that heavy flamer and storm bolter; no twin-linked multi-meltas or heavy bolters allowed. This leads into the Repressor's next big weakness; because it was stuck with a heavy flamer, it had to get really close to enemy units in order to be effective. This was generally fine if it was carrying around infantry, but this weakness became glaringly obvious if it was operating by itself.
|Forces of the Sisters of Battle|
|Command:|| Canoness - Ecclesiarchy Battle Conclave |
Ministorum Priest - Sororitas Command Squad
|Troops:|| Avenging Angel - Arco-flagellant - Battle Sister Squad |
Celestians - Crusaders - Death Cult Assassin
Dominion Squad - Retributor Squad - Seraphim Squad
Sister Hospitaler - Sisters Repentia
|Vehicles:||Exorcist - Immolator - Penitent Engine - Repressor - Rhino|
|Flyers:||Avenger Strike Fighter - Drop Pod|
|Saints:||Living Saint - Geminae Superia|