They don't seem to showcase any of the really impressive abilities, along with pysker traits or sheer power. Vulkan might be considered as well, if not for the fact that he's a Perpetual and cannot die.
Marneus Calgar, he beat an avatar of khaine in single combat, gazghkull is on the run from the black templars and couldnt take helbrecht in a fight so hes less likely to take calgar in a fight, and not to mention beat then later held off M'kar the thriceborn a daemon prince of the word bearers legion when he had entered the materium for a third time
There will always be losses, despite everything the imperium have, every time they launch a crusade into the eye of Terror, they never prevail. What would be the point of guarding the eye with a large number of forces, when they could simply purge it? Furthermore not all 23 Space Marine chapters are guarding the eye, about 4-5 are. It's just when the crusade conquers most of the galaxy, then the Space Marine take notice, and that's when they'll plan to stop the crusade by force. Besides some Space Marine chapters have troubles working together, and working with IG regiments, and inquisitors. For instance, Kronus, need I explain more?
You must be kidding me, Vulkan can't die? as in he literally, can't die? as in immortal? If you were to stab him and crush him, he wouldn't die? Seriously?
One fing 'ere you gitz is fergettin about! Orks are often pigeonholed into story lines in rather uncreative ways, usually as the "oh noes orkz!" which in turn often leads to a larger and apparently more significant threat (oh noes, chaos!). Much like tyranids, orks represent a MASSIVE threat, though they often aren't really given the justice they deserve in the fluff. Ork technology works, because they figure it does. It's a kind of latent psychic aura that grows as more orkz join the group and the more fun (ie WAAAAAGH) they have; This is called a gestalt feild. As more orkz get together, the WAAGH continues and the field grows, often more mekboyz and weirdboyz will show up to exploit it (albeit unintentionally)resulting in things like a utterly massive artillery gun/train/truck the size of a small city, designed to ram into a larger (hive) city and destroy it with a single point blank shot (A scenario, though I can't find it) to massive mechy stompers (Gargants) and such. That said, if you got enough orkz together, and they were creative enough, they could easily make a weapon capable of besting any and all on comers. But is that likely? No, because the fluff never portrays anything nearly as awesome, so it's not really seen as feasibly cannon. Wit dat bit o exposition out of da way, I feel likes gettin me a fungus beer....
Yep. He took a bolter through the head once and survived. He's a perpetual like the Emperor, he cannot be killed. Hell, he's died multiple times in the Horus Heresy series. He's confirmed to be a perpetual like the Emperor, which also ensures that he's one of the few loyalist Primarchs still alive. (Also, this is one of the big reveals as well- the Emperor is a perpetual. The Golden Throne likely isn't actually sustaining him, rather it's a prison.)
... So wait... if Abaddon were to arrive at the gates of Terra, and he stabbed the Emperor, he would STILL be alive?
Eyuup. So long as it wasn't god-killing uber weapon, he should still be very much alive after some regeneration. People also tend to forget the God Emperor is also an actual Warp God and not the human Astartes believe him to be.
