Pretty much all of the epic battle sequences, including:
The Battle of Caraskand at the end of The Warrior Prophet. Beseiged and starving, the Inrithi have turned on each other and sentence Kellhus to Circumfixion. When he miraculously survives and pulls his heart from his own chest, the feeble Inrithi are inspired to heroic deeds. They pour out of the city and attack their far stronger foe, empowered by unconquerable belief, and win.
The Siege of Shimeh, featuring a full throw-down between the Scarlet Spires, the Cishaurim, the Imperial Saik. Achamian's duel with a demon and Kellhus's fight with a half dozen of the top Cishaurim alive also factor into the affair.
In The White Luck Warrior, the Great Ordeal stages a last stand against a tide of sranc while Sorweel's company rides to warn the army of the Ten-Yoke Legion's sneak attack. When Sorweel rides back, he sees what he thinks is a hopeless battle, but soon realizes that the Great Ordeal is singing as they slaughter, that he's not witnessing certain defeat, but glory.
In The Judging Eye, when Mimara banishes the Wight-in-the-Mountain and shuts the gates to the afterlife.
The final scene of The Thousandfold Thought, which doubles as a Tear Jerker.
Almost any time Achamian gets to demonstrate why the Gnosis is so respected. For example, attacking a group of Imperial Saik sorcerers and their Grandmaster, killing all of them single-handed, and then fighting off the most powerful demon Iyokus could send after him.
Achamian and Cleric defeating the Father of Dragons in The White-Luck Warrior.
The giant Oirūnas arriving, in full battle regalia, to take on the Vile court of Ishterebinth.
Kellhus arriving to singlehandedly defeat Fanayal, Meppa, Psatma Nannaferi and Malowebi, while delivering some deadpan snarks along the way.