Warhammer 40,000 Core Rules (5th Edition)
Chaos

Steve: Chaos means demons from a hell-like dimension called the Warp and the humans these evil forces have turned to their cause. There are a bunch of Chaos Space Marines that got turned evil back during the Horus Heresy and now they come through and cause all kinds of trouble for the Imperium.
Zack: They're so much spikier than the regular Space Marines. And the skulls are real and not just symbols.
Steve: Chaos dudes pretty much love four things: spikes, chains, tusks, and severed heads. That's what they're into.
Zack: Even that giant thing in the background is covered with spikes AND tusks. It looks like it actually has multiple tiers of tusks. And a chainsaw bayonet.
Steve: In the grim darkness of the far future all problems are resolved through hand to hand combat.
Zack: "Murray, boss wants the drywall up by eight, so put together a crew of berzerkers with chain-axes."
Steve: It sounds implausible, but I bet after you tally up all the dice rolls that drywall will be hanging.
Zack: Great, only now the whole place smells like skulls.
