Thanks to the machine spirit aiding his Mark VII Power Armor, Tiberius heard, or rather felt the faint tremors along the floors as a veritable horde approached the group in droves. It was his instinct that told him their allegiance, and the large Adeptus Astartes held himself against the wall to strike in their midst rather than before them. It was in the split second when he saw the mutant at the fore that he knew his intuition to be correct. 

He stepped out into the main hall, his powersword now lit and thrumming with a fury that matched its wielder. His very steps wrought destruction, crushing some smaller heretic's legs as he waded forward. With a strength beyond them, and a blur of movement, Tiberius had sheared through three heretics and a mutant. "By the Emperor's creed, you shall be punished!" he cried, hacking apart four more and using his free hand to literally bash the skull in of a heretic. 

He felt claws and makeshift weapons itch across his armor, but it did little to harm him. Even the autoguns at full capacity gave the lightest of dents in his armor. "To me, brothers!" He called to the other Black Templars, carving a way back toward them, allowing them to spearhead into the enemy's ranks and exploit the chink of weakness in their lines. With a final hack, he had cleared the way, blood pooling along the floor. 

It still was not enough for Tiberius' reckoning.