A List of things considered Awesome in the fanfic of The Coffin of Roboute and His 20 Sisters
Roboute Guilliman/Malum Caedo ( Primarch of the Ultramarines):
Roboute effortlessly dispatch the stormcloaks belonging to Asarni in a sparring match.
Roboute's choice of arrival on Olympia, crashing down onto the mountain of Dammekos. Surviving without a scratch and firghtening everyone with his panoply of war and style of arrival.
Roboute managed to save Morrigan while exposed to the poison of Rotigus, a Great Unclean One who was empowered by a planet-wide ritual.
Petra ( Primarch of the Iron Warriors):
Petra was able to analyse anything and anyone, deducing their weaknesses in an instant. The one exception? The Emperor's sword and shield.
Petra standing firmly in the face of a stranger giant who claimed to be her brother and telling him his prophets are wrong.
The Tech-Priest Magos Calculatus explaining that weaknesses in things are permissible if the tradeoff is that the material cost is lower and their effectiveness remains the same, like for non-combat units. When Petra says that she can still improve the design of a Servo-skull without increasing the cost of manufacture, Calculatus challenges her to attempt it, because if she fails she will learn a valuable lesson from it, and if she succeeds she will create something exceptional, and it will be a wonderful blessing for the Cult Mechanicus. Whatever the outcome, it will be a win regardless.
Kassandra ( Primarch of the Night Lords)
Kassandra was able to survive on Nostramo for a certain period of time by her lonesome.
Aurelia
A subdued case as Aurelia managed to held on to hope for so long through the horrific abuse of Kor Phaeron was an impressive feat, something every Sexual Assault victim wished they have. In addition, she decided to act out because she sensed her brother's psychic presence forcing them to punish her which will give Roboute the incentive to deliver vengeance.
Morrigan
Prior to her brother's arrival, Morrigan was able to rally a majority of the common folk of Barbarus together and gave them home.
The Emperor
The Emperor, after discovering his psychic powers, honed them by going to Atlantis, which by this point had become a nest of daemons of eldritch horrors (and it's implied it's also this universe's version R'lyeh) and spending centuries killing everything.
Upon seeing the fireworks used by Madonna, The Emperor returned the gesture in kind by placing on a psychic image of a golden sword, surpassing the largest pyramids of Prospero and frightening every psyker on the planet.
Malwyrn
Malwyrn's Badass Boast as he blast his way through the fortress and cities of Colchis. Malwyrn's Boast
“BY THE LICENSE OF MY GOD NAMED ASURYAN, AND MY GODDESS NAMED ISHA, I ADVANCED AND MARCHED AGAINST UMLAUT, KING OF THE WORLDS THAT HAD NOT BOWED TO MY YOKE.”
“I CONQUERED, I DESTROYED, I DEMOLISHED, AND BURNED WITH FIRE FOURTEEN OF HIS WORLDS, TWELVE OF HIS SYSTEM-DISTRICTS, SIX OF HIS ROYAL PALACES, AND HIS SETTLEMENTS WHICH WERE WITHOUT NUMBER WITHIN THE EMPIRE RAGNA-ELD, ALL OF IT.”
“I TURNED THEM INTO MOUNDS AND RUINS. I SLEW HIS WAR-SLAVES WITHOUT NUMBER. I STRUCK DOWN HIS VETERAN SWORDSMEN WITH MY LANCE, AND THE WIDOWS OF THE KING OF THOSE WORLDS FLED NAKED INTO THE VOID BEYOND THE WHEEL.”
“AS FOR THE PEOPLE LIVING INSIDE THEM, I ANNIHILATED THEM. I SHATTERED THEIR FALSE-IDOLS AND THUS PLACATED MY GODS. I CARRIED OFF TO MY HOMELAND THEIR GODS, THEIR GODDESSES, ITS POSSESSIONS, ITS PROPERTY, AND ITS PEOPLE. OVER AN AREA OF SIXTY CONTINENTS, BY THE COMMAND OF MY GOD ASURYAN AND MY GODDESS ISHA, I ENTERED THE EMPIRE RAGNA-ELD AND TRAMPLED IT UNDERFOOT.”
The distinguished Wraithknight proves capable of taking on a Great Unclean One. The battle was glorious.