Tamina, using the Hassansin leader Zolm's own pet snake to give him a Family-Unfriendly Death by forcing it to bite him in the eye!
The part during Sand-trap scene when Dastan pulls that last-minute back-flip to safety was honestly pretty epic.
Dastan hitting the Reset Button during the climax, rewinding time to back when he first got the dagger. What follows is Dastan using his knowledge of what he learned to expose Nizam's villainy and Set Right What Once Went Wrong, therefore saving the lives of everyone that had died in the first timeline.
On that note, how Nizam is exposed is a moment of awesome that can be entirely put down to Tus, the insecure heir to his father's throne. The course of the new timeline depends entirely on who he chooses to believe, his brother or his uncle. Unable to choose, he takes a third option befitting of a wise king: he commands that the spy who reported the supposed existence of Alamut's secret weapons stashes be brought to him so he can confirm the truth. He doesn't even need to get as far as interrogating the spy as Nizam, realising how screwed he was, completely loses his shit and attacks Dastan, exposing his treachery anyway. Tus proceeds to defend his brother by killing Nizam himself.
As the released sands of time come for him, what does King Shahraman do? Pull out his sword and slice away at the waves before they overwhelm him. He fails, but the fact he was willing to fight to the end shows he was a valorous king in life and death.
"Call me, Kakulukiyam". Imagine a random word used to be just a memory of the past, gets used to earn the trust of a girl in a new timeline. So even if Farah forgot the original memories from the past, the feeling of awe that someone else knows a secret that you never told others at all, means that she's understood how the power of time is amazing.