What regiment they were? I need it... for scientific purposes.
The Only Light Brigade of the Emperor's 314th Honourable Regiment, using Cadian guardsmen
Amongst the hero Melta guardsman was the guardsman simply known as 'Blood Guy.'
He was a medic, 'Blood Guy,' who became nigh-legendary when his command squad was attacked by the C'Tan Nighbringer. Veterans all around him, officers and commissars with the oldest and most powerful of wargear all around him, all were effortlessly killed by this resurgent god of death. Despite Blood Guy's best efforts, he simply couldn't fix total bisection. Eventually Blood Guy was the last man standing - he passed his morale test, deciding that he was more than happy to fight a god in close quarters combat armed with nothing but lots of blood packs. Second round of CQC, the god of war is unharmed, but so is blood guy. Third round of CQC, the god of war is unharmed, but so is blood guy. This goes on and on until at last on the fourth bout, blood guy gets downed. A shadowsword takes notice of this heroism and promptly unleashes all of its titan-killing glory upon the C'Tan, until the C'Tan explodes. The shadowsword then gets covered in scarabs, at which point the shadowsword explodes and destroys the scarabs.
From then on it became a recurring theme, that whenever the C'Tan and Blood Guy were on the same board, they had to fight to the death. I like to imagine Blood Guy staring down death, and laughing, because death forgot to bring his own blood pack