Chapter Master Smashfucker
Smashfucker is one of the most cheesey, rapey, deadly character builds in Warhammer 40,000. An Iron Hands Chapter Master with a monstrous set of wargear, he is practically immortal and will smash your shit with extreme prejudice.
Codex: Space Marines version
Smashbane, Smashfucker's original incarnation, is an Iron Hands Chapter Master on a bike, with Artificer Armour, the Shield Eternal and a weapon (usually a Thunder Hammer), as well as usually having Digital Weapons. This gives him 4 wounds,toughness 5, a 2+ armour save and a 3++ invulnerable save, 6+ Feel No Pain, 6+ It Will Not Die, and Eternal Warrior. If you take a Thunder Hammer - and there's really no reason not to, you're paying so much for him as it is that there's no point in trying to save points - you'll be hitting at strength 8, AP2 with Concussive, and you won't need to worry about initiative as you're not going to die anyway. While he won't win against everyone - notably, he'll (mathematically) lose against both the Swarmlord and Ghazghkull - he's still dead 'ard and dead killy.
Clan Raukaan Supplement version
With the release of the Clan Raukaan supplement, Smashbane evolved into Smashfucker: although he can't take the Shield Eternal any more, he can now take the even better Gorgon's Chain. This piece of gear doesn't take up a weapons slot, unlike the Shield, and not only do you get 3++ and Eternal Warrior, you ALSO get +1 to your Feel No Pain! The only downside to this is that its effectiveness decreases as you take wounds, first losing the Feel No Pain boost, then the Eternal Warrior, and then having its 3++ decreased to a 4++. However, you're unlikely to get that far, and if you regain wounds with your IWND, you get the previous levels of the Chain back! As it doesn't take up a weapon slot, you can use that for a Lightning Claw - giving you an extra attack and the chance to strike at initiative - or the Betrayer's Bane, an infinite-use Combi-Melta. If you really want to bottle up the tears of your opponent, you can take the Mindforge Stave, a force Thunder Hammer for some sweet instant death. And if you got the Warlord Trait that gives you an EXTRA +1 to your FnP, then your opponent may as well save himself the trouble and surrender.
If you field it, they will die. Almost nothing short of a Daemon Prince of Nurgle wielding the Black Mace can even touch this guy, and even then the Daemon Prince might lose.