Elysian Drop Troops
Elysian drop troops use tactics along the lines of using rapid deployment to throw troops straight into enemy lines. They are famed in battles such as the Taros campaign, the Anphelion project and defence of Betalys. They come from Elysia, a planet about 30 light years away from Armageddon. Elysians are well trained in ship-to-ship boarding actions, and fighting in concert with orbital support when attacking enemies. Hilariously enough, in pretty much all canon conflicts they take part in they get dicked over for one reason or another, though it's always due to incompetent command, betrayal of some allies or the fuck-ups of other regiments. Maybe they're getting slapped with some kind of bad luck, or there's some heresy going on at Forge World. Most tellingly, anything involving them and the Ultramarines tends to result in the Elysians getting fucked over whenever the Ultramines (inevitably and always) end up failing. So...nothing new there. That's ok, though, we all know the guys who survived the Taros campaign and inevitably surrendered are getting fucktons of heretical blue xeno ass.
Training Elysians usually include throwing kids from the back of moving Valkyries until they learn to use grav chutes, or being shown how to clusterfuck even Orks from behind with only a lasgun. It is a good time to mention that the Guardsmen being trained to do these kinds of things all volunteered to do this, which adds some rather wiry hairs to their massive steel balls. They also often employ Drop Sentinels and the Tauros and Venator vehicles because the Leman Russ Battle Tank is too ponderous for their way of deployment.
In 6-th edition with ability to spam flyers from hell to breakfast Elysians turned from intersting tactical army to cheesy cheese of cheese, broken far beyond anything you face before. Though, like with Grey Knight you can create ballanced and interesting army with lots of deep strikeing guardsman, multimelta srntinels and heavy (but not cheesy heavy) flyer support if you do not want to be a power gamer douche. And by "can" we actually mean "must", unless you want to be beaten to death with old metal dreadnought models by your fellows in local wargame club.
We have a tactica for this guys, it's here.