The Forsaken run from their tower at me, a mass of tribal weapons and old magic, full of implacable rage. They descend as a mass, striking at me. I stand firm. Blows from hairy cudgels and sharpened giant's toenails bounce off my Dark Angel power armour, as I wait for them to tire. Once they have worn themselves grey, I unload my Plasma Pistol at the nearest one. Before it fries him and his stupid beard, it knocks him right across the clearing. Then I pull my chainsword, to what I imagine are their puzzled frowns. 'Is that Dwemer?' they must be thinking as I tramp heavily over to them... cue buzzing, screams and the occasional tear.
The Warhammer 40K pack for Skyrim gives you a whole bunch of Space Marine accessories from Games Workshop's darker-than-sin-and-twice-as-fun future universe. I came here to tell you that they're awesome, basically.
In terms of the Aquila VII armour, you can make it easily, cheaply and quickly at any forge just with gold - it doesn't require any special materials. Each piece is enchantable, but comes with a special ability to represent the power armour's tech. It's also ridiculously overpowered - tougher than almost anything that I've come across in the unmodded game.
The weaponry is equally ludicrous; 19 weapons ranging from a Dwemer autoblade (chainsword) and Chaplain Crozius, to Plasma Pistols and Bolt Pistols. Again, they can be crafted at the forge - but they're so cheap to make and valuable, they will break your game's economy. They're also over-powered and over-sized, for reasons that will become apparent. My favourite line from the patch notes has to be "Bolt pistol bolt is too fast to see; this is not an accident."
Someone has gone to extreme levels to include as many Space Marine chapters as possible, with all the old favourites in there (Blood Angels, Dark Angels, Space Wolves, and as well as the non-Canon Angry Marines. Race options have also been modified to include several of the chapters.
Finally, the pack includes a doubled jump height option, as well a scaling tome that allows the player to acquire a lesser power that makes him 20% bigger - roughly the size of a standard Space Marine.